diff --git a/lib/internal/test_runner/test.js b/lib/internal/test_runner/test.js
index 48271e2e71a80e..0d2e0ab6e5acd6 100644
--- a/lib/internal/test_runner/test.js
+++ b/lib/internal/test_runner/test.js
@@ -247,7 +247,9 @@ class Test extends AsyncResource {
     }
 
     if (testOnlyFlag && !this.only) {
-      skip = '\'only\' option not set';
+      skip = "'only' option not set";
+    } else if (!testOnlyFlag && (only || this.runOnlySubtests)) {
+      this.emitOnlyWarning = true;
     }
 
     if (skip) {
@@ -710,6 +712,13 @@ class Test extends AsyncResource {
     for (let i = 0; i < this.diagnostics.length; i++) {
       this.reporter.diagnostic(this.nesting, kFilename, this.diagnostics[i]);
     }
+
+    if (this.emitOnlyWarning) {
+      const warning =
+        "to use 'only' or 'runOnly' in the test runner" +
+        ' run node with the --test-only command-line option.';
+      this.reporter.diagnostic(this.nesting, kFilename, warning);
+    }
   }
 
   reportStarted() {
diff --git a/test/message/test_runner_output.out b/test/message/test_runner_output.out
index 15d2009816a961..2774e32142eef5 100644
--- a/test/message/test_runner_output.out
+++ b/test/message/test_runner_output.out
@@ -475,11 +475,13 @@ ok 52 - callback async throw after done
       ---
       duration_ms: *
       ...
+    # to use 'only' or 'runOnly' in the test runner run node with the --test-only command-line option.
     # Subtest: running subtest 3
     ok 3 - running subtest 3
       ---
       duration_ms: *
       ...
+    # to use 'only' or 'runOnly' in the test runner run node with the --test-only command-line option.
     # Subtest: running subtest 4
     ok 4 - running subtest 4
       ---
@@ -490,6 +492,7 @@ ok 53 - only is set but not in only mode
   ---
   duration_ms: *
   ...
+# to use 'only' or 'runOnly' in the test runner run node with 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..bbb8e03e589cdd 100644
--- a/test/message/test_runner_output_cli.out
+++ b/test/message/test_runner_output_cli.out
@@ -476,11 +476,13 @@ TAP version 13
           ---
           duration_ms: *
           ...
+        # to use 'only' or 'runOnly' in the test runner run node with the --test-only command-line option.
         # Subtest: running subtest 3
         ok 3 - running subtest 3
           ---
           duration_ms: *
           ...
+        # to use 'only' or 'runOnly' in the test runner run node with the --test-only command-line option.
         # Subtest: running subtest 4
         ok 4 - running subtest 4
           ---
@@ -491,6 +493,7 @@ TAP version 13
       ---
       duration_ms: *
       ...
+    # to use 'only' or 'runOnly' in the test runner run node with 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..3d066fc58733cb 100644
--- a/test/message/test_runner_output_spec_reporter.out
+++ b/test/message/test_runner_output_spec_reporter.out
@@ -199,9 +199,12 @@
  only is set but not in only mode
    running subtest 1 (*ms)
    running subtest 2 (*ms)
+   to use 'only' or 'runOnly' in the test runner run node with the --test-only command-line option.
    running subtest 3 (*ms)
+   to use 'only' or 'runOnly' in the test runner run node with the --test-only command-line option.
    running subtest 4 (*ms)
  only is set but not in only mode (*ms)
+ to use 'only' or 'runOnly' in the test runner run node with the --test-only command-line option.
 
  custom inspect symbol fail (*ms)
   customized