diff --git a/packages/angular_devkit/schematics_cli/bin/schematics.ts b/packages/angular_devkit/schematics_cli/bin/schematics.ts
index d370edf98227..02272044c568 100644
--- a/packages/angular_devkit/schematics_cli/bin/schematics.ts
+++ b/packages/angular_devkit/schematics_cli/bin/schematics.ts
@@ -96,6 +96,13 @@ function _createPromptProvider(): schema.PromptProvider {
           )({
             message: definition.message,
             default: definition.default,
+            validate: (values) => {
+              if (!definition.validator) {
+                return true;
+              }
+
+              return definition.validator(Object.values(values).map(({ value }) => value));
+            },
             choices: definition.items.map((item) =>
               typeof item == 'string'
                 ? {