diff --git a/akka-stream/src/main/scala/akka/stream/javadsl/Flow.scala b/akka-stream/src/main/scala/akka/stream/javadsl/Flow.scala
index e1ca98ffd5..1fda46d15d 100644
--- a/akka-stream/src/main/scala/akka/stream/javadsl/Flow.scala
+++ b/akka-stream/src/main/scala/akka/stream/javadsl/Flow.scala
@@ -988,6 +988,7 @@ final class Flow[-In, +Out, +Mat](delegate: scaladsl.Flow[In, Out, Mat]) extends
    * This operator makes it possible to extend the `Flow` API when there is no specialized
    * operator that performs the transformation.
    */
+  @deprecated("Use via(GraphStage) instead.", "2.4.3")
   def transform[U](mkStage: function.Creator[Stage[Out, U]]): javadsl.Flow[In, U, Mat] =
     new Flow(delegate.transform(() ⇒ mkStage.create()))
 
diff --git a/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala b/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala
index 8afcee3fc9..c681f776b8 100644
--- a/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala
+++ b/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala
@@ -1428,6 +1428,7 @@ final class Source[+Out, +Mat](delegate: scaladsl.Source[Out, Mat]) extends Grap
    * This operator makes it possible to extend the `Flow` API when there is no specialized
    * operator that performs the transformation.
    */
+  @deprecated("Use via(GraphStage) instead.", "2.4.3")
   def transform[U](mkStage: function.Creator[Stage[Out, U]]): javadsl.Source[U, Mat] =
     new Source(delegate.transform(() ⇒ mkStage.create()))
 
diff --git a/akka-stream/src/main/scala/akka/stream/javadsl/SubFlow.scala b/akka-stream/src/main/scala/akka/stream/javadsl/SubFlow.scala
index 3ee680a20f..d8a1c593e6 100644
--- a/akka-stream/src/main/scala/akka/stream/javadsl/SubFlow.scala
+++ b/akka-stream/src/main/scala/akka/stream/javadsl/SubFlow.scala
@@ -837,6 +837,7 @@ class SubFlow[-In, +Out, +Mat](delegate: scaladsl.SubFlow[Out, Mat, scaladsl.Flo
    * This operator makes it possible to extend the `Flow` API when there is no specialized
    * operator that performs the transformation.
    */
+  @deprecated("Use via(GraphStage) instead.", "2.4.3")
   def transform[U](mkStage: function.Creator[Stage[Out, U]]): SubFlow[In, U, Mat] =
     new SubFlow(delegate.transform(() ⇒ mkStage.create()))
 
diff --git a/akka-stream/src/main/scala/akka/stream/javadsl/SubSource.scala b/akka-stream/src/main/scala/akka/stream/javadsl/SubSource.scala
index e966b9a764..4336ec4b45 100644
--- a/akka-stream/src/main/scala/akka/stream/javadsl/SubSource.scala
+++ b/akka-stream/src/main/scala/akka/stream/javadsl/SubSource.scala
@@ -835,6 +835,7 @@ class SubSource[+Out, +Mat](delegate: scaladsl.SubFlow[Out, Mat, scaladsl.Source
    * This operator makes it possible to extend the `Flow` API when there is no specialized
    * operator that performs the transformation.
    */
+  @deprecated("Use via(GraphStage) instead.", "2.4.3")
   def transform[U](mkStage: function.Creator[Stage[Out, U]]): SubSource[U, Mat] =
     new SubSource(delegate.transform(() ⇒ mkStage.create()))
 
diff --git a/akka-stream/src/main/scala/akka/stream/scaladsl/Flow.scala b/akka-stream/src/main/scala/akka/stream/scaladsl/Flow.scala
index 595aa5c723..e0e21b73de 100644
--- a/akka-stream/src/main/scala/akka/stream/scaladsl/Flow.scala
+++ b/akka-stream/src/main/scala/akka/stream/scaladsl/Flow.scala
@@ -1103,6 +1103,7 @@ trait FlowOps[+Out, +Mat] {
    * This operator makes it possible to extend the `Flow` API when there is no specialized
    * operator that performs the transformation.
    */
+  @deprecated("Use via(GraphStage) instead.", "2.4.3")
   def transform[T](mkStage: () ⇒ Stage[Out, T]): Repr[T] =
     via(new PushPullGraphStage((attr) ⇒ mkStage(), Attributes.none))