diff --git a/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/compute.json b/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/compute.json
index ae2f79b3d3f8..a8eb59a0600d 100644
--- a/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/compute.json
+++ b/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/compute.json
@@ -4469,6 +4469,327 @@
         }
       }
     },
+    "/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.Compute/virtualMachineScaleSets/{vmScaleSetName}/virtualMachines/{instanceId}/extensions/{vmExtensionName}": {
+      "put": {
+        "tags": [
+            "VirtualMachineScaleSetVMExtensions"
+        ],
+        "operationId": "VirtualMachineScaleSetVMExtensions_CreateOrUpdate",
+        "description": "The operation to create or update the VMSS VM extension.",
+        "parameters": [
+          {
+            "name": "resourceGroupName",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The name of the resource group."
+          },
+          {
+            "name": "vmScaleSetName",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The name of the VM scale set."
+          },
+          {
+            "name": "instanceId",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The instance ID of the virtual machine."
+          },
+          {
+            "name": "vmExtensionName",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The name of the virtual machine extension."
+          },
+          {
+            "name": "extensionParameters",
+            "in": "body",
+            "required": true,
+            "schema": {
+              "$ref": "#/definitions/VirtualMachineExtension"
+            },
+            "description": "Parameters supplied to the Create Virtual Machine Extension operation."
+          },
+          {
+            "$ref": "#/parameters/ApiVersionParameter"
+          },
+          {
+            "$ref": "#/parameters/SubscriptionIdParameter"
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "OK",
+            "schema": {
+              "$ref": "#/definitions/VirtualMachineExtension"
+            }
+          },
+          "201": {
+            "description": "Created",
+            "schema": {
+              "$ref": "#/definitions/VirtualMachineExtension"
+            }
+          }
+        },
+        "x-ms-long-running-operation": true,
+        "x-ms-examples": {
+          "Create VirtualMachineScaleSet VM extension.": {
+            "$ref": "./examples/CreateOrUpdateVirtualMachineScaleSetVMExtensions.json"
+          }
+        }
+      },
+      "patch": {
+        "tags": [
+            "VirtualMachineScaleSetVMExtensions"
+        ],
+        "operationId": "VirtualMachineScaleSetVMExtensions_Update",
+        "description": "The operation to update the VMSS VM extension.",
+        "parameters": [
+          {
+            "name": "resourceGroupName",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The name of the resource group."
+          },
+          {
+            "name": "vmScaleSetName",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The name of the VM scale set."
+          },
+          {
+            "name": "instanceId",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The instance ID of the virtual machine."
+          },
+          {
+            "name": "vmExtensionName",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The name of the virtual machine extension."
+          },
+          {
+            "name": "extensionParameters",
+            "in": "body",
+            "required": true,
+            "schema": {
+              "$ref": "#/definitions/VirtualMachineExtensionUpdate"
+            },
+            "description": "Parameters supplied to the Update Virtual Machine Extension operation."
+          },
+          {
+            "$ref": "#/parameters/ApiVersionParameter"
+          },
+          {
+            "$ref": "#/parameters/SubscriptionIdParameter"
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "OK",
+            "schema": {
+              "$ref": "#/definitions/VirtualMachineExtension"
+            }
+          }
+        },
+        "x-ms-long-running-operation": true,
+        "x-ms-examples": {
+          "Update VirtualMachineScaleSet VM extension.": {
+            "$ref": "./examples/UpdateVirtualMachineScaleSetVMExtensions.json"
+          }
+        }
+      },
+      "delete": {
+        "tags": [
+          "VirtualMachineScaleSetVMExtensions"
+        ],
+        "operationId": "VirtualMachineScaleSetVMExtensions_Delete",
+        "description": "The operation to delete the VMSS VM extension.",
+        "parameters": [
+          {
+            "name": "resourceGroupName",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The name of the resource group."
+          },
+          {
+            "name": "vmScaleSetName",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The name of the VM scale set."
+          },
+          {
+            "name": "instanceId",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The instance ID of the virtual machine."
+          },
+          {
+            "name": "vmExtensionName",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The name of the virtual machine extension."
+          },
+          {
+            "$ref": "#/parameters/ApiVersionParameter"
+          },
+          {
+            "$ref": "#/parameters/SubscriptionIdParameter"
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "OK"
+          },
+          "202": {
+            "description": "Accepted"
+          },
+          "204": {
+            "description": "No Content"
+          }
+        },
+        "x-ms-long-running-operation": true,
+        "x-ms-examples": {
+          "Delete VirtualMachineScaleSet VM extension.": {
+            "$ref": "./examples/DeleteVirtualMachineScaleSetVMExtensions.json"
+          }
+        }
+      },
+      "get": {
+        "tags": [
+          "VirtualMachineScaleSetVMExtensions"
+        ],
+        "operationId": "VirtualMachineScaleSetVMExtensions_Get",
+        "description": "The operation to get the VMSS VM extension.",
+        "parameters": [
+          {
+            "name": "resourceGroupName",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The name of the resource group."
+          },
+          {
+            "name": "vmScaleSetName",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The name of the VM scale set."
+          },
+          {
+            "name": "instanceId",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The instance ID of the virtual machine."
+          },
+          {
+            "name": "vmExtensionName",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The name of the virtual machine extension."
+          },
+          {
+            "name": "$expand",
+            "in": "query",
+            "required": false,
+            "type": "string",
+            "description": "The expand expression to apply on the operation."
+          },
+          {
+            "$ref": "#/parameters/ApiVersionParameter"
+          },
+          {
+            "$ref": "#/parameters/SubscriptionIdParameter"
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "OK",
+            "schema": {
+              "$ref": "#/definitions/VirtualMachineExtension"
+            }
+          }
+        },
+        "x-ms-examples": {
+          "Get VirtualMachineScaleSet VM extension.": {
+            "$ref": "./examples/GetVirtualMachineScaleSetVMExtensions.json"
+          }
+        }
+      }
+    },
+    "/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.Compute/virtualMachineScaleSets/{vmScaleSetName}/virtualMachines/{instanceId}/extensions": {
+      "get": {
+        "tags": [
+            "VirtualMachineScaleSetVMExtensions"
+        ],
+        "operationId": "VirtualMachineScaleSetVMExtensions_List",
+        "description": "The operation to get all extensions of an instance in Virtual Machine Scaleset.",
+        "parameters": [
+          {
+            "name": "resourceGroupName",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The name of the resource group."
+          },
+          {
+            "name": "vmScaleSetName",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The name of the VM scale set."
+          },
+          {
+            "name": "instanceId",
+            "in": "path",
+            "required": true,
+            "type": "string",
+            "description": "The instance ID of the virtual machine."
+          },
+          {
+            "name": "$expand",
+            "in": "query",
+            "required": false,
+            "type": "string",
+            "description": "The expand expression to apply on the operation."
+          },
+          {
+            "$ref": "#/parameters/ApiVersionParameter"
+          },
+          {
+            "$ref": "#/parameters/SubscriptionIdParameter"
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "OK",
+            "schema": {
+              "$ref": "#/definitions/VirtualMachineExtensionsListResult"
+            }
+          }
+        },
+        "x-ms-examples": {
+          "List extensions in Vmss instance.": {
+            "$ref": "./examples/ListVirtualMachineScaleSetVMExtensions.json"
+          }
+        }
+      }
+    },
     "/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.Compute/virtualMachineScaleSets/{vmScaleSetName}/virtualmachines/{instanceId}/reimage": {
       "post": {
         "tags": [
diff --git a/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/examples/CreateOrUpdateVirtualMachineScaleSetVMExtensions.json b/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/examples/CreateOrUpdateVirtualMachineScaleSetVMExtensions.json
new file mode 100644
index 000000000000..080c96490c75
--- /dev/null
+++ b/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/examples/CreateOrUpdateVirtualMachineScaleSetVMExtensions.json
@@ -0,0 +1,54 @@
+{
+    "parameters": {
+      "subscriptionId": "{subscription-id}",
+      "resourceGroupName": "myResourceGroup",
+      "vmScaleSetName": "myvmScaleSet",
+      "instanceId": "0",
+      "vmExtensionName":"myVMExtension",
+      "api-version": "2019-07-01",
+      "extensionParameters": {
+        "location": "westus",
+        "properties": {
+            "autoUpgradeMinorVersion": true,
+            "publisher": "extPublisher",
+            "type": "extType",
+            "typeHandlerVersion": "1.2",
+            "settings": { "UserName": "xyz@microsoft.com" }
+        }
+      }
+    },
+    "responses": {
+      "201": {
+        "body": {
+          "name": "myVMExtension",
+          "location": "westus",
+          "type":"Microsoft.Compute/virtualMachineScaleSets/virtualMachines/extensions",
+          "id": "/subscriptions/{subscriptionId}/resourceGroups/myResourceGroup/providers/Microsoft.Compute/virtualMachineScaleSets/myvmScaleSet/virtualMachines/0/extensions/myVMExtension",
+          "properties": {
+            "autoUpgradeMinorVersion": true,
+            "provisioningState": "Creating",
+            "publisher": "extPublisher",
+            "type": "extType",
+            "typeHandlerVersion": "1.2",
+            "settings": {"UserName":"xyz@microsoft.com"}
+          }
+        }
+      },
+      "200": {
+        "body": {
+            "name": "myVMExtension",
+            "location": "westus",
+            "type":"Microsoft.Compute/virtualMachineScaleSets/virtualMachines/extensions",
+            "id": "/subscriptions/{subscriptionId}/resourceGroups/myResourceGroup/providers/Microsoft.Compute/virtualMachineScaleSets/myvmScaleSet/virtualMachines/0/extensions/myVMExtension",
+            "properties": {
+                "autoUpgradeMinorVersion": true,
+                "provisioningState": "Creating",
+                "publisher": "extPublisher",
+                "type": "extType",
+                "typeHandlerVersion": "1.2",
+                "settings": {"UserName":"xyz@microsoft.com"}
+            }
+        }
+      }
+    }
+  }
diff --git a/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/examples/DeleteVirtualMachineScaleSetVMExtensions.json b/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/examples/DeleteVirtualMachineScaleSetVMExtensions.json
new file mode 100644
index 000000000000..caba488648b0
--- /dev/null
+++ b/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/examples/DeleteVirtualMachineScaleSetVMExtensions.json
@@ -0,0 +1,15 @@
+{
+    "parameters": {
+      "subscriptionId": "{subscription-id}",
+      "resourceGroupName": "myResourceGroup",
+      "vmScaleSetName": "myvmScaleSet",
+      "instanceId": "0",
+      "vmExtensionName":"myVMExtension",
+      "api-version": "2019-07-01"
+    },
+    "responses": {
+      "200": {},
+      "202": {},
+      "204": {}
+    }
+  }
diff --git a/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/examples/GetVirtualMachineScaleSetVMExtensions.json b/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/examples/GetVirtualMachineScaleSetVMExtensions.json
new file mode 100644
index 000000000000..5af5fe255613
--- /dev/null
+++ b/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/examples/GetVirtualMachineScaleSetVMExtensions.json
@@ -0,0 +1,28 @@
+{
+    "parameters": {
+      "subscriptionId": "{subscription-id}",
+      "resourceGroupName": "myResourceGroup",
+      "vmScaleSetName": "myvmScaleSet",
+      "instanceId": "0",
+      "vmExtensionName":"myVMExtension",
+      "api-version": "2019-07-01"
+    },
+    "responses": {
+      "200": {
+        "body": {
+            "properties": {
+                "autoUpgradeMinorVersion": true,
+                "provisioningState": "Creating",
+                "publisher": "extPublisher",
+                "type": "extType",
+                "typeHandlerVersion": "1.2",
+                "settings": {"UserName":"xyz@microsoft.com"}
+            },
+            "name": "myVMExtension",
+            "location": "westus",
+            "type":"Microsoft.Compute/virtualMachineScaleSets/virtualMachines/extensions",
+            "id": "/subscriptions/{subscriptionId}/resourceGroups/myResourceGroup/providers/Microsoft.Compute/virtualMachineScaleSets/myvmScaleSet/virtualMachines/0/extensions/myVMExtension"
+        }
+      }
+    }
+  }
diff --git a/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/examples/ListVirtualMachineScaleSetVMExtensions.json b/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/examples/ListVirtualMachineScaleSetVMExtensions.json
new file mode 100644
index 000000000000..234274c9440b
--- /dev/null
+++ b/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/examples/ListVirtualMachineScaleSetVMExtensions.json
@@ -0,0 +1,45 @@
+{
+    "parameters": {
+      "subscriptionId": "{subscription-id}",
+      "resourceGroupName": "myResourceGroup",
+      "vmScaleSetName": "myvmScaleSet",
+      "instanceId": "0",
+      "api-version": "2019-07-01"
+    },
+    "responses": {
+      "200": {
+        "body": {
+          "value": [
+            {
+              "properties": {
+                "autoUpgradeMinorVersion": true,
+                "provisioningState": "Succeeded",
+                "publisher": "extPublisher",
+                "type": "extType",
+                "typeHandlerVersion": "1.2",
+                "settings": {"UserName":"xyz@microsoft.com"}
+            },
+            "name": "myVMExtension",
+            "location": "westus",
+            "type":"Microsoft.Compute/virtualMachineScaleSets/virtualMachines/extensions",
+            "id": "/subscriptions/{subscriptionId}/resourceGroups/myResourceGroup/providers/Microsoft.Compute/virtualMachineScaleSets/myvmScaleSet/virtualMachines/0/extensions/myVMExtension"
+            },
+            {
+              "properties": {
+                "autoUpgradeMinorVersion": true,
+                "provisioningState": "Succeeded",
+                "publisher": "extPublisher1",
+                "type": "extType1",
+                "typeHandlerVersion": "1.0",
+                "settings": {"UserName":"xyz@microsoft.com"}
+            },
+            "name": "myVMExtension1",
+            "location": "westus",
+            "type":"Microsoft.Compute/virtualMachineScaleSets/virtualMachines/extensions",
+            "id": "/subscriptions/{subscriptionId}/resourceGroups/myResourceGroup/providers/Microsoft.Compute/virtualMachineScaleSets/myvmScaleSet/virtualMachines/0/extensions/myVMExtension1"
+            }
+          ]
+      }
+    }
+  }
+}
diff --git a/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/examples/UpdateVirtualMachineScaleSetVMExtensions.json b/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/examples/UpdateVirtualMachineScaleSetVMExtensions.json
new file mode 100644
index 000000000000..913b1afdee28
--- /dev/null
+++ b/specification/compute/resource-manager/Microsoft.Compute/stable/2019-07-01/examples/UpdateVirtualMachineScaleSetVMExtensions.json
@@ -0,0 +1,37 @@
+{
+    "parameters": {
+      "subscriptionId": "{subscription-id}",
+      "resourceGroupName": "myResourceGroup",
+      "vmScaleSetName": "myvmScaleSet",
+      "instanceId": "0",
+      "vmExtensionName":"myVMExtension",
+      "api-version": "2019-07-01",
+      "extensionParameters": {
+        "properties": {
+            "autoUpgradeMinorVersion": true,
+            "publisher": "extPublisher",
+            "type": "extType",
+            "typeHandlerVersion": "1.2",
+            "settings": { "UserName": "xyz@microsoft.com" }
+        }
+      }
+    },
+    "responses": {
+      "200": {
+        "body": {
+            "name": "myVMExtension",
+            "location": "westus",
+            "type":"Microsoft.Compute/virtualMachineScaleSets/virtualMachines/extensions",
+            "id": "/subscriptions/{subscriptionId}/resourceGroups/myResourceGroup/providers/Microsoft.Compute/virtualMachineScaleSets/myvmScaleSet/virtualMachines/0/extensions/myVMExtension",
+            "properties": {
+                "autoUpgradeMinorVersion": true,
+                "provisioningState": "Creating",
+                "publisher": "extPublisher",
+                "type": "extType",
+                "typeHandlerVersion": "1.2",
+                "settings": {"UserName":"xyz@microsoft.com"}
+            }
+        }
+      }
+    }
+  }