diff --git a/akka-docs/src/main/paradox/project/migration-guide-2.5.x-2.6.x.md b/akka-docs/src/main/paradox/project/migration-guide-2.5.x-2.6.x.md
index 89efd9a958..0d1d94ebbf 100644
--- a/akka-docs/src/main/paradox/project/migration-guide-2.5.x-2.6.x.md
+++ b/akka-docs/src/main/paradox/project/migration-guide-2.5.x-2.6.x.md
@@ -596,7 +596,7 @@ used for individual streams when they are materialized.
 | `streamRefSettings.demandRedeliveryInterval` | `StreamRefAttributes.demandRedeliveryInterval`  | `akka.stream.materializer.stream-ref.demand-redelivery-interval` |
 | `streamRefSettings.subscriptionTimeout`      | `StreamRefAttributes.subscriptionTimeout`       | `akka.stream.materializer.stream-ref.subscription-timeout` |
 | `streamRefSettings.finalTerminationSignalDeadline` | `StreamRefAttributes.finalTerminationSignalDeadline` | `akka.stream.materializer.stream-ref.final-termination-signal-deadline` |
-| `blockingIoDispatcher`                       | `ActorAttributes.blockingIoDispatcher`          | `akka.stream.materializer.blocking-io-dispatcher` |
+| `blockingIoDispatcher`                       | na                                              | `akka.stream.materializer.blocking-io-dispatcher` |
 | `subscriptionTimeoutSettings.mode`           | `ActorAttributes.streamSubscriptionTimeoutMode` | `akka.stream.materializer.subscription-timeout.mode` |
 | `subscriptionTimeoutSettings.timeout`        | `ActorAttributes.streamSubscriptionTimeout`     | `akka.stream.materializer.subscription-timeout.timeout` |
 
diff --git a/akka-stream/src/main/scala/akka/stream/ActorMaterializer.scala b/akka-stream/src/main/scala/akka/stream/ActorMaterializer.scala
index 666b31c8fe..7c027cde5d 100644
--- a/akka-stream/src/main/scala/akka/stream/ActorMaterializer.scala
+++ b/akka-stream/src/main/scala/akka/stream/ActorMaterializer.scala
@@ -779,8 +779,7 @@ final class ActorMaterializerSettings @InternalApi private (
       ActorAttributes.OutputBurstLimit(outputBurstLimit) ::
       ActorAttributes.FuzzingMode(fuzzingMode) ::
       ActorAttributes.MaxFixedBufferSize(maxFixedBufferSize) ::
-      ActorAttributes.SyncProcessingLimit(syncProcessingLimit) ::
-      ActorAttributes.BlockingIoDispatcher(blockingIoDispatcher) :: Nil)
+      ActorAttributes.SyncProcessingLimit(syncProcessingLimit) :: Nil)
 
   override def toString: String =
     s"ActorMaterializerSettings($initialInputBufferSize,$maxInputBufferSize," +
diff --git a/akka-stream/src/main/scala/akka/stream/Attributes.scala b/akka-stream/src/main/scala/akka/stream/Attributes.scala
index e0e50cb7ae..e80c736799 100644
--- a/akka-stream/src/main/scala/akka/stream/Attributes.scala
+++ b/akka-stream/src/main/scala/akka/stream/Attributes.scala
@@ -588,12 +588,6 @@ object ActorAttributes {
   def syncProcessingLimit(limit: Int): Attributes =
     Attributes(SyncProcessingLimit(limit))
 
-  /**
-   * FIXME Is this really needed anymore now that we have indirect dispatcher config?
-   */
-  final case class BlockingIoDispatcher(dispatcher: String) extends MandatoryAttribute
-  def blockingIoDispatcher(dispatcher: String): Attributes =
-    Attributes(BlockingIoDispatcher(dispatcher))
 }
 
 /**
diff --git a/akka-stream/src/main/scala/akka/stream/impl/ActorMaterializerImpl.scala b/akka-stream/src/main/scala/akka/stream/impl/ActorMaterializerImpl.scala
index 4f58de4dc8..3e0ea42bbf 100644
--- a/akka-stream/src/main/scala/akka/stream/impl/ActorMaterializerImpl.scala
+++ b/akka-stream/src/main/scala/akka/stream/impl/ActorMaterializerImpl.scala
@@ -57,11 +57,8 @@ import scala.concurrent.Future
   @InternalApi private[akka] override def actorOf(context: MaterializationContext, props: Props): ActorRef = {
     val effectiveProps = props.dispatcher match {
       case Dispatchers.DefaultDispatcherId =>
+        // the caller said to use the default dispatcher, but that can been trumped by the dispatcher attribute
         props.withDispatcher(context.effectiveAttributes.mandatoryAttribute[ActorAttributes.Dispatcher].dispatcher)
-      case ActorAttributes.IODispatcher.dispatcher =>
-        // this one is actually not a dispatcher but a relative config key pointing containing the actual dispatcher name
-        val actual = context.effectiveAttributes.mandatoryAttribute[ActorAttributes.BlockingIoDispatcher].dispatcher
-        props.withDispatcher(actual)
       case _ => props
     }
 
diff --git a/akka-stream/src/main/scala/akka/stream/impl/PhasedFusingActorMaterializer.scala b/akka-stream/src/main/scala/akka/stream/impl/PhasedFusingActorMaterializer.scala
index ac1a027bc0..e56048aef7 100644
--- a/akka-stream/src/main/scala/akka/stream/impl/PhasedFusingActorMaterializer.scala
+++ b/akka-stream/src/main/scala/akka/stream/impl/PhasedFusingActorMaterializer.scala
@@ -625,10 +625,6 @@ private final case class SavedIslandData(
     val effectiveProps = props.dispatcher match {
       case Dispatchers.DefaultDispatcherId =>
         props.withDispatcher(context.effectiveAttributes.mandatoryAttribute[ActorAttributes.Dispatcher].dispatcher)
-      case ActorAttributes.IODispatcher.dispatcher =>
-        // this one is actually not a dispatcher but a relative config key pointing containing the actual dispatcher name
-        // FIXME go via attributes here,or something
-        props.withDispatcher(settings.blockingIoDispatcher)
       case _ => props
     }