diff --git a/lib/internal/test_runner/test.js b/lib/internal/test_runner/test.js
index 48271e2e71a80e..c51fdc4a925951 100644
--- a/lib/internal/test_runner/test.js
+++ b/lib/internal/test_runner/test.js
@@ -288,6 +288,13 @@ class Test extends AsyncResource {
     };
     this.waitingOn = 0;
     this.finished = false;
+
+    if (!testOnlyFlag && only) {
+      const warning =
+        "'only' does not work when node is started" +
+        ' without the --test-only command-line option';
+      this.diagnostic(warning);
+    }
   }
 
   hasConcurrency() {
diff --git a/test/message/test_runner_only_warning.js b/test/message/test_runner_only_warning.js
new file mode 100644
index 00000000000000..88aed49ab453d6
--- /dev/null
+++ b/test/message/test_runner_only_warning.js
@@ -0,0 +1,9 @@
+'use strict';
+require('../common');
+const { test } = require('node:test');
+
+test('only = true without --test-only flag', { only: true }, () => {});
+
+test('subtest only = true without --test-only flag', (t) => {
+  t.test('this subtest is run', { only: true });
+});
diff --git a/test/message/test_runner_only_warning.out b/test/message/test_runner_only_warning.out
new file mode 100644
index 00000000000000..2906e51298ef1f
--- /dev/null
+++ b/test/message/test_runner_only_warning.out
@@ -0,0 +1,27 @@
+TAP version 13
+# Subtest: only = true without --test-only flag
+ok 1 - only = true without --test-only flag
+  ---
+  duration_ms: *
+  ...
+# 'only' does not work when node is started without the --test-only command-line option
+# Subtest: subtest only = true without --test-only flag
+    # Subtest: this subtest is run
+    ok 1 - this subtest is run
+      ---
+      duration_ms: *
+      ...
+    # 'only' does not work when node is started without the --test-only command-line option
+    1..1
+ok 2 - subtest only = true without --test-only flag
+  ---
+  duration_ms: *
+  ...
+1..2
+# tests 2
+# pass 2
+# fail 0
+# cancelled 0
+# skipped 0
+# todo 0
+# duration_ms *
diff --git a/test/message/test_runner_output.out b/test/message/test_runner_output.out
index 15d2009816a961..7c87e360c959cf 100644
--- a/test/message/test_runner_output.out
+++ b/test/message/test_runner_output.out
@@ -480,6 +480,7 @@ ok 52 - callback async throw after done
       ---
       duration_ms: *
       ...
+    # 'only' does not work when node is started without the --test-only command-line option
     # Subtest: running subtest 4
     ok 4 - running subtest 4
       ---
@@ -490,6 +491,7 @@ ok 53 - only is set but not in only mode
   ---
   duration_ms: *
   ...
+# 'only' does not work when node is started without the --test-only command-line option
 # Subtest: custom inspect symbol fail
 not ok 54 - custom inspect symbol fail
   ---
diff --git a/test/message/test_runner_output_cli.out b/test/message/test_runner_output_cli.out
index cc9c07f4c5c409..bb1e4f19434945 100644
--- a/test/message/test_runner_output_cli.out
+++ b/test/message/test_runner_output_cli.out
@@ -481,6 +481,7 @@ TAP version 13
           ---
           duration_ms: *
           ...
+        # 'only' does not work when node is started without the --test-only command-line option
         # Subtest: running subtest 4
         ok 4 - running subtest 4
           ---
@@ -491,6 +492,7 @@ TAP version 13
       ---
       duration_ms: *
       ...
+    # 'only' does not work when node is started without the --test-only command-line option
     # Subtest: custom inspect symbol fail
     not ok 54 - custom inspect symbol fail
       ---
diff --git a/test/message/test_runner_output_spec_reporter.out b/test/message/test_runner_output_spec_reporter.out
index cf47c7ac7e33ff..9025f318920ee0 100644
--- a/test/message/test_runner_output_spec_reporter.out
+++ b/test/message/test_runner_output_spec_reporter.out
@@ -200,8 +200,10 @@
    running subtest 1 (*ms)
    running subtest 2 (*ms)
    running subtest 3 (*ms)
+   'only' does not work when node is started without the --test-only command-line option
    running subtest 4 (*ms)
  only is set but not in only mode (*ms)
+ 'only' does not work when node is started without the --test-only command-line option
 
  custom inspect symbol fail (*ms)
   customized