diff --git a/python/src/com/jetbrains/python/inspections/PyDataclassInspection.kt b/python/src/com/jetbrains/python/inspections/PyDataclassInspection.kt
index 1562bddaa9cf..5cc044a8cfb8 100644
--- a/python/src/com/jetbrains/python/inspections/PyDataclassInspection.kt
+++ b/python/src/com/jetbrains/python/inspections/PyDataclassInspection.kt
@@ -90,6 +90,7 @@ class PyDataclassInspection : PyInspection() {
               ?.also { processAttrsPostInitDefinition(it, dataclassParameters) }
 
             processAttrsDefaultThroughDecorator(node)
+            processAttrsInitializersAndValidators(node)
           }
 
           PyNamedTupleInspection.inspectFieldsOrder(
@@ -361,6 +362,41 @@ class PyDataclassInspection : PyInspection() {
       }
     }
 
+    private fun processAttrsInitializersAndValidators(cls: PyClass) {
+      cls.visitMethods(
+        { method ->
+          val decorators = method.decoratorList?.decorators
+
+          if (decorators != null) {
+            decorators
+              .asSequence()
+              .mapNotNull { it.qualifiedName }
+              .filter { it.componentCount == 2 }
+              .mapNotNull { it.lastComponent }
+              .forEach {
+                val expectedParameters = when (it) {
+                  "default" -> 1
+                  "validator" -> 3
+                  else -> return@forEach
+                }
+
+                val actualParameters = method.parameterList
+                if (actualParameters.parameters.size != expectedParameters) {
+                  val message = "'${method.name}' should take only $expectedParameters parameter" +
+                                if (expectedParameters > 1) "s" else ""
+
+                  registerProblem(actualParameters, message, ProblemHighlightType.GENERIC_ERROR)
+                }
+              }
+          }
+
+          true
+        },
+        false,
+        myTypeEvalContext
+      )
+    }
+
     private fun processAsInitVar(field: PyTargetExpression, postInit: PyFunction?): PyTargetExpression? {
       if (isInitVar(field)) {
         if (postInit == null) {
diff --git a/python/testData/inspections/PyDataclassInspection/attrsInitializersAndValidators.py b/python/testData/inspections/PyDataclassInspection/attrsInitializersAndValidators.py
new file mode 100644
index 000000000000..6920342366a8
--- /dev/null
+++ b/python/testData/inspections/PyDataclassInspection/attrsInitializersAndValidators.py
@@ -0,0 +1,27 @@
+import attr
+
+
+@attr.s
+class A:
+    x = attr.ib()
+
+    @x.default
+    def init_x1(self):
+        return 10
+
+    @x.validator
+    def check_x1(self, attribute, value):
+        pass
+
+
+@attr.s
+class A:
+    x = attr.ib()
+
+    @x.default
+    def init_x2<error descr="'init_x2' should take only 1 parameter">(self, attribute, value)</error>:
+        return 10
+
+    @x.validator
+    def check_x2<error descr="'check_x2' should take only 3 parameters">(self)</error>:
+        pass
\ No newline at end of file
diff --git a/python/testSrc/com/jetbrains/python/inspections/PyDataclassInspectionTest.java b/python/testSrc/com/jetbrains/python/inspections/PyDataclassInspectionTest.java
index f40b2ad47fe5..fa97b88cd5e2 100644
--- a/python/testSrc/com/jetbrains/python/inspections/PyDataclassInspectionTest.java
+++ b/python/testSrc/com/jetbrains/python/inspections/PyDataclassInspectionTest.java
@@ -161,6 +161,11 @@ public class PyDataclassInspectionTest extends PyInspectionTestCase {
     doTest();
   }
 
+  // PY-26354
+  public void testAttrsInitializersAndValidators() {
+    doTest();
+  }
+
   @Override
   protected void doTest() {
     runWithLanguageLevel(