diff --git a/.changelog/34716.txt b/.changelog/34716.txt
new file mode 100644
index 00000000000..dff67cc970b
--- /dev/null
+++ b/.changelog/34716.txt
@@ -0,0 +1,7 @@
+```release-note:bug
+resource/aws_ecr_pull_through_cache_rule: Fix plan time validation for `ecr_repository_prefix`
+```
+
+```release-note:bug
+data-source/aws_ecr_pull_through_cache_rule: Fix plan time validation for `ecr_repository_prefix`
+```
diff --git a/internal/service/ecr/pull_through_cache_rule.go b/internal/service/ecr/pull_through_cache_rule.go
index de356d55963..4e68b4339ab 100644
--- a/internal/service/ecr/pull_through_cache_rule.go
+++ b/internal/service/ecr/pull_through_cache_rule.go
@@ -35,10 +35,10 @@ func ResourcePullThroughCacheRule() *schema.Resource {
 				Required: true,
 				ForceNew: true,
 				ValidateFunc: validation.All(
-					validation.StringLenBetween(2, 20),
+					validation.StringLenBetween(2, 30),
 					validation.StringMatch(
-						regexache.MustCompile(`^[0-9a-z]+(?:[._-][0-9a-z]+)*$`),
-						"must only include alphanumeric, underscore, period, or hyphen characters"),
+						regexache.MustCompile(`(?:[a-z0-9]+(?:[._-][a-z0-9]+)*/)*[a-z0-9]+(?:[._-][a-z0-9]+)*`),
+						"must only include alphanumeric, underscore, period, hyphen, or slash characters"),
 				),
 			},
 			"registry_id": {
diff --git a/internal/service/ecr/pull_through_cache_rule_data_source.go b/internal/service/ecr/pull_through_cache_rule_data_source.go
index 65bd8491754..036e7ccba77 100644
--- a/internal/service/ecr/pull_through_cache_rule_data_source.go
+++ b/internal/service/ecr/pull_through_cache_rule_data_source.go
@@ -24,10 +24,10 @@ func DataSourcePullThroughCacheRule() *schema.Resource {
 				Required: true,
 				ForceNew: true,
 				ValidateFunc: validation.All(
-					validation.StringLenBetween(2, 20),
+					validation.StringLenBetween(2, 30),
 					validation.StringMatch(
-						regexache.MustCompile(`^[0-9a-z]+(?:[._-][0-9a-z]+)*$`),
-						"must only include alphanumeric, underscore, period, or hyphen characters"),
+						regexache.MustCompile(`(?:[a-z0-9]+(?:[._-][a-z0-9]+)*/)*[a-z0-9]+(?:[._-][a-z0-9]+)*`),
+						"must only include alphanumeric, underscore, period, hyphen, or slash characters"),
 				),
 			},
 			"registry_id": {
diff --git a/internal/service/ecr/pull_through_cache_rule_data_source_test.go b/internal/service/ecr/pull_through_cache_rule_data_source_test.go
index f0e1ef7b84a..2d349153da6 100644
--- a/internal/service/ecr/pull_through_cache_rule_data_source_test.go
+++ b/internal/service/ecr/pull_through_cache_rule_data_source_test.go
@@ -4,9 +4,11 @@
 package ecr_test
 
 import (
+	"fmt"
 	"testing"
 
 	"github.com/aws/aws-sdk-go/service/ecr"
+	sdkacctest "github.com/hashicorp/terraform-plugin-testing/helper/acctest"
 	"github.com/hashicorp/terraform-plugin-testing/helper/resource"
 	"github.com/hashicorp/terraform-provider-aws/internal/acctest"
 )
@@ -31,6 +33,28 @@ func TestAccECRPullThroughCacheRuleDataSource_basic(t *testing.T) {
 	})
 }
 
+func TestAccECRPullThroughCacheRuleDataSource_repositoryPrefixWithSlash(t *testing.T) {
+	ctx := acctest.Context(t)
+	repositoryPrefix := "tf-test/" + sdkacctest.RandString(22)
+	dataSource := "data.aws_ecr_pull_through_cache_rule.test"
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:                 func() { acctest.PreCheck(ctx, t) },
+		ErrorCheck:               acctest.ErrorCheck(t, ecr.EndpointsID),
+		ProtoV5ProviderFactories: acctest.ProtoV5ProviderFactories,
+		CheckDestroy:             testAccCheckPullThroughCacheRuleDestroy(ctx),
+		Steps: []resource.TestStep{
+			{
+				Config: testAccPullThroughCacheRuleDataSourceConfig_repositoryPrefixWithSlash(repositoryPrefix),
+				Check: resource.ComposeTestCheckFunc(
+					resource.TestCheckResourceAttr(dataSource, "upstream_registry_url", "public.ecr.aws"),
+					acctest.CheckResourceAttrAccountID(dataSource, "registry_id"),
+				),
+			},
+		},
+	})
+}
+
 func testAccPullThroughCacheRuleDataSourceConfig_basic() string {
 	return `
 resource "aws_ecr_pull_through_cache_rule" "test" {
@@ -43,3 +67,16 @@ data "aws_ecr_pull_through_cache_rule" "test" {
 }
 `
 }
+
+func testAccPullThroughCacheRuleDataSourceConfig_repositoryPrefixWithSlash(repositoryPrefix string) string {
+	return fmt.Sprintf(`
+resource "aws_ecr_pull_through_cache_rule" "test" {
+  ecr_repository_prefix = %[1]q
+  upstream_registry_url = "public.ecr.aws"
+}
+
+data "aws_ecr_pull_through_cache_rule" "test" {
+  ecr_repository_prefix = aws_ecr_pull_through_cache_rule.test.ecr_repository_prefix
+}
+`, repositoryPrefix)
+}
diff --git a/internal/service/ecr/pull_through_cache_rule_test.go b/internal/service/ecr/pull_through_cache_rule_test.go
index a7afde6da90..9e4dcb48765 100644
--- a/internal/service/ecr/pull_through_cache_rule_test.go
+++ b/internal/service/ecr/pull_through_cache_rule_test.go
@@ -97,6 +97,30 @@ func TestAccECRPullThroughCacheRule_failWhenAlreadyExists(t *testing.T) {
 	})
 }
 
+func TestAccECRPullThroughCacheRule_repositoryPrefixWithSlash(t *testing.T) {
+	ctx := acctest.Context(t)
+	repositoryPrefix := "tf-test/" + sdkacctest.RandString(22)
+	resourceName := "aws_ecr_pull_through_cache_rule.test"
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:                 func() { acctest.PreCheck(ctx, t) },
+		ErrorCheck:               acctest.ErrorCheck(t, ecr.EndpointsID),
+		ProtoV5ProviderFactories: acctest.ProtoV5ProviderFactories,
+		CheckDestroy:             testAccCheckPullThroughCacheRuleDestroy(ctx),
+		Steps: []resource.TestStep{
+			{
+				Config: testAccPullThroughCacheRuleConfig_basic(repositoryPrefix),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckPullThroughCacheRuleExists(ctx, resourceName),
+					resource.TestCheckResourceAttr(resourceName, "ecr_repository_prefix", repositoryPrefix),
+					testAccCheckPullThroughCacheRuleRegistryID(resourceName),
+					resource.TestCheckResourceAttr(resourceName, "upstream_registry_url", "public.ecr.aws"),
+				),
+			},
+		},
+	})
+}
+
 func testAccCheckPullThroughCacheRuleDestroy(ctx context.Context) resource.TestCheckFunc {
 	return func(s *terraform.State) error {
 		conn := acctest.Provider.Meta().(*conns.AWSClient).ECRConn(ctx)