diff --git a/lib/src/lucid_validation_builder.dart b/lib/src/lucid_validation_builder.dart
index 066df91..8a40470 100644
--- a/lib/src/lucid_validation_builder.dart
+++ b/lib/src/lucid_validation_builder.dart
@@ -63,6 +63,14 @@ abstract class LucidValidationBuilder<TProp, Entity> {
   /// The [key] can be used to identify this specific validation in a larger validation context.
   LucidValidationBuilder(this.key, this._selector);
 
+  String? Function([String?]) nestedByField(Entity entity, String key) {
+    if (_nestedValidator == null) {
+      return ([_]) => null;
+    }
+
+    return _nestedValidator!.byField(_selector(entity), key);
+  }
+
   /// Registers a validation rule for the property.
   ///
   /// [validator] is a function that returns `true` if the property is valid and `false` otherwise.
diff --git a/lib/src/lucid_validator.dart b/lib/src/lucid_validator.dart
index 7d24a7a..2d913f0 100644
--- a/lib/src/lucid_validator.dart
+++ b/lib/src/lucid_validator.dart
@@ -18,7 +18,7 @@ abstract class LucidValidator<E> {
   /// final validator = UserValidation();
   /// validator.ruleFor((user) => user.email).validEmail();
   /// ```
-  LucidValidationBuilder<TProp, E> ruleFor<TProp>(TProp Function(E entity) selector, {String key = ''}) {
+  LucidValidationBuilder<TProp, E> ruleFor<TProp>(TProp Function(E entity) selector, {required String key}) {
     final builder = _LucidValidationBuilder<TProp, E>(key, selector);
     _builders.add(builder);
 
@@ -36,23 +36,39 @@ abstract class LucidValidator<E> {
   /// String? validationResult = emailValidator('user@example.com');
   /// ```
   String? Function([String?]) byField(E entity, String key) {
-    final builder = _builders
+    if (key.contains('.')) {
+      final keys = key.split('.');
+
+      final firstKey = keys.removeAt(0);
+      final builder = _getBuilderByKey(firstKey);
+      if (builder == null) {
+        return ([_]) => null;
+      }
+
+      return builder.nestedByField(entity, keys.join('.'));
+    } else {
+      final builder = _getBuilderByKey(key);
+
+      if (builder == null) {
+        return ([_]) => null;
+      }
+
+      return ([_]) {
+        final errors = builder.executeRules(entity);
+        if (errors.isNotEmpty) {
+          return errors.first.message;
+        }
+        return null;
+      };
+    }
+  }
+
+  LucidValidationBuilder? _getBuilderByKey(String key) {
+    return _builders
         .where(
           (builder) => builder.key == key,
         )
         .firstOrNull;
-
-    if (builder == null) {
-      return ([_]) => null;
-    }
-
-    return ([_]) {
-      final errors = builder.executeRules(entity);
-      if (errors.isNotEmpty) {
-        return errors.first.message;
-      }
-      return null;
-    };
   }
 
   /// Validates the entire entity [E] and returns a list of [ValidationError]s if any rules fail.
@@ -70,8 +86,8 @@ abstract class LucidValidator<E> {
   /// }
   /// ```
   ValidationResult validate(E entity) {
-    final errors = _builders.fold(<ValidationError>[], (previousErrors, errors) {
-      return previousErrors..addAll(errors.executeRules(entity));
+    final errors = _builders.fold(<ValidationError>[], (previousErrors, builder) {
+      return previousErrors..addAll(builder.executeRules(entity));
     });
 
     return ValidationResult(
diff --git a/test/byfield_validation_test.dart b/test/byfield_validation_test.dart
new file mode 100644
index 0000000..8560041
--- /dev/null
+++ b/test/byfield_validation_test.dart
@@ -0,0 +1,118 @@
+import 'package:lucid_validation/lucid_validation.dart';
+import 'package:test/test.dart';
+
+import 'mocks/mocks.dart';
+
+void main() {
+  test('byfield normal', () {
+    final validator = TestLucidValidator<UserModel>();
+
+    validator.ruleFor((model) => model.age, key: 'age').greaterThan(17);
+    validator.ruleFor((model) => model.email, key: 'email').notEmpty();
+
+    final user = UserModel()..age = 16;
+
+    final ageValidator = validator.byField(user, 'age');
+
+    expect(ageValidator(), isNotNull);
+
+    user.age = 18;
+
+    expect(ageValidator(), null);
+
+    final emailValidator = validator.byField(user, 'email');
+
+    expect(emailValidator(), isNotNull);
+
+    user.email = 'test@gmail.com';
+
+    expect(emailValidator(), null);
+  });
+
+  group('nested byfield normal', () {
+    final flagValidator = TestLucidValidator<Flag>();
+    flagValidator.ruleFor((flag) => flag.value, key: 'value').equalTo((entity) => true);
+
+    final categoryValidator = TestLucidValidator<CategoryModel>();
+    categoryValidator.ruleFor((category) => category.name, key: 'name').notEmpty();
+    categoryValidator.ruleFor((category) => category.flag, key: 'flag').setValidator(flagValidator);
+
+    final productValidator = TestLucidValidator<ProductModel>();
+    productValidator.ruleFor((product) => product.name, key: 'name').notEmpty();
+    productValidator.ruleFor((product) => product.price, key: 'price').greaterThan(0);
+    productValidator.ruleFor((product) => product.category, key: 'category').setValidator(categoryValidator);
+
+    final product = ProductModel();
+
+    test('nameValidator', () {
+      final nameValidator = productValidator.byField(product, 'name');
+      expect(nameValidator(), isNotNull);
+    });
+
+    test('priceValidator', () {
+      final priceValidator = productValidator.byField(product, 'price');
+      expect(priceValidator(), isNotNull);
+    });
+
+    test('categoryValidator', () {
+      final categoryValidatorFn = productValidator.byField(product, 'category');
+      expect(categoryValidatorFn(), isNotNull);
+    });
+
+    test('categoryNameValidator', () {
+      final categoryNameValidatorFn = productValidator.byField(product, 'category.name');
+      expect(categoryNameValidatorFn(), isNotNull);
+    });
+
+    test('flagValidator', () {
+      final flagValidatorFn = productValidator.byField(product, 'category.flag');
+      expect(flagValidatorFn(), isNotNull);
+    });
+
+    test('flagValueValidator', () {
+      final flagValueValidatorFn = productValidator.byField(product, 'category.flag.value');
+      expect(flagValueValidatorFn(), isNotNull);
+    });
+
+    test('must return null if not found key', () {
+      final flagValueValidatorFn = productValidator.byField(product, 'category.flag.notExists');
+      expect(flagValueValidatorFn(), null);
+    });
+
+    test('all validators', () {
+      product.name = 'Product';
+      product.price = 10;
+      product.category.name = 'Category';
+      product.category.flag.value = true;
+
+      final nameValidator = productValidator.byField(product, 'name');
+      final priceValidator = productValidator.byField(product, 'price');
+      final categoryValidatorFn = productValidator.byField(product, 'category');
+      final categoryNameValidatorFn = productValidator.byField(product, 'category.name');
+      final flagValidatorFn = productValidator.byField(product, 'category.flag');
+      final flagValueValidatorFn = productValidator.byField(product, 'category.flag.value');
+
+      expect(nameValidator(), null);
+      expect(priceValidator(), null);
+      expect(categoryValidatorFn(), null);
+      expect(categoryNameValidatorFn(), null);
+      expect(flagValidatorFn(), null);
+      expect(flagValueValidatorFn(), null);
+    });
+  });
+}
+
+class ProductModel {
+  String name = '';
+  double price = 0.0;
+  CategoryModel category = CategoryModel();
+}
+
+class CategoryModel {
+  String name = '';
+  Flag flag = Flag();
+}
+
+class Flag {
+  bool value = false;
+}