diff --git a/beacon_node/http_api/src/lib.rs b/beacon_node/http_api/src/lib.rs
index d6993c8fcbc..e088ee08205 100644
--- a/beacon_node/http_api/src/lib.rs
+++ b/beacon_node/http_api/src/lib.rs
@@ -2571,7 +2571,7 @@ pub async fn serve<T: BeaconChainTypes>(
         task_spawner_filter.clone(),
     );
 
-    // GET validator/execution_payload_envelopes/{slot}/{builder_index}
+    // GET validator/execution_payload_envelopes/{slot}/{beacon_block_root}
     let get_validator_execution_payload_envelopes = get_validator_execution_payload_envelopes(
         eth_v1.clone(),
         chain_filter.clone(),
diff --git a/beacon_node/http_api/src/validator/execution_payload_envelopes.rs b/beacon_node/http_api/src/validator/execution_payload_envelopes.rs
index e5c9cbe0db1..e038bbb8f0f 100644
--- a/beacon_node/http_api/src/validator/execution_payload_envelopes.rs
+++ b/beacon_node/http_api/src/validator/execution_payload_envelopes.rs
@@ -8,10 +8,10 @@ use eth2::types::Accept;
 use ssz::Encode;
 use std::sync::Arc;
 use tracing::debug;
-use types::Slot;
+use types::{Hash256, Slot};
 use warp::{Filter, Rejection, http::response::Builder, reply::Reply};
 
-// GET validator/execution_payload_envelopes/{slot}
+// GET validator/execution_payload_envelopes/{slot}/{beacon_block_root}
 pub fn get_validator_execution_payload_envelopes<T: BeaconChainTypes>(
     eth_v1: EthV1Filter,
     chain_filter: ChainFilter<T>,
@@ -26,6 +26,11 @@ pub fn get_validator_execution_payload_envelopes<T: BeaconChainTypes>(
                 "Invalid slot".to_string(),
             ))
         }))
+        .and(warp::path::param::<Hash256>().or_else(|_| async {
+            Err(warp_utils::reject::custom_bad_request(
+                "Invalid beacon_block_root".to_string(),
+            ))
+        }))
         .and(warp::path::end())
         .and(warp::header::optional::<Accept>("accept"))
         .and(not_while_syncing_filter)
@@ -33,24 +38,26 @@ pub fn get_validator_execution_payload_envelopes<T: BeaconChainTypes>(
         .and(chain_filter)
         .then(
             |slot: Slot,
+             beacon_block_root: Hash256,
              accept_header: Option<Accept>,
              not_synced_filter: Result<(), Rejection>,
              task_spawner: TaskSpawner<T::EthSpec>,
              chain: Arc<BeaconChain<T>>| {
                 task_spawner.spawn_async_with_rejection(Priority::P0, async move {
-                    debug!(?slot, "Execution payload envelope request from HTTP API");
+                    debug!(?slot, ?beacon_block_root, "Execution payload envelope request from HTTP API");
 
                     not_synced_filter?;
 
-                    // Get the envelope from the pending cache (local building only)
+                    // Get the envelope from the pending cache (local building only).
                     let envelope = chain
                         .pending_payload_envelopes
                         .read()
                         .get(slot)
+                        .filter(|envelope| envelope.beacon_block_root == beacon_block_root)
                         .cloned()
                         .ok_or_else(|| {
                             warp_utils::reject::custom_not_found(format!(
-                                "Execution payload envelope not available for slot {slot}"
+                                "Execution payload envelope not available for slot {slot} and root {beacon_block_root:?}"
                             ))
                         })?;
 
diff --git a/beacon_node/http_api/tests/tests.rs b/beacon_node/http_api/tests/tests.rs
index bd2a6f17559..b5d4b65c35b 100644
--- a/beacon_node/http_api/tests/tests.rs
+++ b/beacon_node/http_api/tests/tests.rs
@@ -4441,13 +4441,24 @@ impl ApiTester {
 
             let envelope = self
                 .client
-                .get_validator_execution_payload_envelopes::<E>(slot)
+                .get_validator_execution_payload_envelopes::<E>(slot, block.tree_hash_root())
                 .await
                 .unwrap()
                 .data;
 
             self.assert_envelope_fields(&envelope, block.tree_hash_root(), slot);
 
+            // A request for a root this node did not build must miss (reorg-resistance).
+            assert!(
+                self.client
+                    .get_validator_execution_payload_envelopes::<E>(
+                        slot,
+                        Hash256::repeat_byte(0xff)
+                    )
+                    .await
+                    .is_err()
+            );
+
             let signed_block = block.sign(&sk, &fork, genesis_validators_root, &self.chain.spec);
             let signed_block_request =
                 PublishBlockRequest::try_from(Arc::new(signed_block.clone())).unwrap();
@@ -4503,7 +4514,7 @@ impl ApiTester {
 
             let envelope = self
                 .client
-                .get_validator_execution_payload_envelopes_ssz::<E>(slot)
+                .get_validator_execution_payload_envelopes_ssz::<E>(slot, block.tree_hash_root())
                 .await
                 .unwrap();
 
@@ -4963,7 +4974,7 @@ impl ApiTester {
             // Retrieve and publish the envelope.
             let envelope = self
                 .client
-                .get_validator_execution_payload_envelopes::<E>(slot)
+                .get_validator_execution_payload_envelopes::<E>(slot, block_root)
                 .await
                 .unwrap()
                 .data;
diff --git a/common/eth2/src/lib.rs b/common/eth2/src/lib.rs
index 24bb873992a..2154c524441 100644
--- a/common/eth2/src/lib.rs
+++ b/common/eth2/src/lib.rs
@@ -2761,10 +2761,11 @@ impl BeaconNodeHttpClient {
         opt_response.ok_or(Error::StatusCode(StatusCode::NOT_FOUND))
     }
 
-    /// `GET v1/validator/execution_payload_envelopes/{slot}`
+    /// `GET v1/validator/execution_payload_envelopes/{slot}/{beacon_block_root}`
     pub async fn get_validator_execution_payload_envelopes<E: EthSpec>(
         &self,
         slot: Slot,
+        beacon_block_root: Hash256,
     ) -> Result<ForkVersionedResponse<ExecutionPayloadEnvelope<E>>, Error> {
         let mut path = self.eth_path(V1)?;
 
@@ -2772,15 +2773,17 @@ impl BeaconNodeHttpClient {
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
             .push("validator")
             .push("execution_payload_envelopes")
-            .push(&slot.to_string());
+            .push(&slot.to_string())
+            .push(&beacon_block_root.to_string());
 
         self.get(path).await
     }
 
-    /// `GET v1/validator/execution_payload_envelopes/{slot}` in SSZ format
+    /// `GET v1/validator/execution_payload_envelopes/{slot}/{beacon_block_root}` in SSZ format
     pub async fn get_validator_execution_payload_envelopes_ssz<E: EthSpec>(
         &self,
         slot: Slot,
+        beacon_block_root: Hash256,
     ) -> Result<ExecutionPayloadEnvelope<E>, Error> {
         let mut path = self.eth_path(V1)?;
 
@@ -2788,7 +2791,8 @@ impl BeaconNodeHttpClient {
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
             .push("validator")
             .push("execution_payload_envelopes")
-            .push(&slot.to_string());
+            .push(&slot.to_string())
+            .push(&beacon_block_root.to_string());
 
         let opt_response = self
             .get_bytes_opt_accept_header(path, Accept::Ssz, self.timeouts.get_validator_block)
diff --git a/validator_client/validator_services/src/block_service.rs b/validator_client/validator_services/src/block_service.rs
index 06fd14360a1..c953c581603 100644
--- a/validator_client/validator_services/src/block_service.rs
+++ b/validator_client/validator_services/src/block_service.rs
@@ -14,7 +14,7 @@ use std::time::Duration;
 use task_executor::TaskExecutor;
 use tokio::sync::mpsc;
 use tracing::{Instrument, debug, error, info, info_span, instrument, trace, warn};
-use types::{BlockType, ChainSpec, EthSpec, Graffiti, Slot};
+use types::{BlockType, ChainSpec, EthSpec, Graffiti, Hash256, Slot};
 use validator_store::{Error as ValidatorStoreError, SignedBlock, UnsignedBlock, ValidatorStore};
 
 #[derive(Debug)]
@@ -611,6 +611,11 @@ impl<S: ValidatorStore + 'static, T: SlotClock + 'static> BlockService<S, T> {
             ));
         }
 
+        // Capture before `sign_and_publish_block` moves `unsigned_block`.
+        let produced_block_root = fork_name
+            .gloas_enabled()
+            .then(|| unsigned_block.block_root());
+
         self_ref
             .sign_and_publish_block(
                 &proposer_fallback,
@@ -624,11 +629,12 @@ impl<S: ValidatorStore + 'static, T: SlotClock + 'static> BlockService<S, T> {
         // TODO(gloas) we only need to fetch, sign and publish the envelope in the local building case.
         // Right now we always default to local building. Once we implement trustless/trusted builder logic
         // we should check the bid for index == BUILDER_INDEX_SELF_BUILD
-        if fork_name.gloas_enabled() {
+        if let Some(beacon_block_root) = produced_block_root {
             self_ref
                 .fetch_sign_and_publish_payload_envelope(
                     &proposer_fallback,
                     slot,
+                    beacon_block_root,
                     &validator_pubkey,
                 )
                 .await?;
@@ -649,17 +655,21 @@ impl<S: ValidatorStore + 'static, T: SlotClock + 'static> BlockService<S, T> {
         &self,
         _proposer_fallback: &ProposerFallback<T>,
         slot: Slot,
+        beacon_block_root: Hash256,
         validator_pubkey: &PublicKeyBytes,
     ) -> Result<(), BlockError> {
-        info!(slot = slot.as_u64(), "Fetching execution payload envelope");
+        info!(
+            slot = slot.as_u64(),
+            %beacon_block_root,
+            "Fetching execution payload envelope"
+        );
 
         // Fetch the envelope from the beacon node.
-        // TODO(gloas): Use proposer_fallback once multi-BN is supported.
         let envelope = self
             .beacon_nodes
             .first_success(|beacon_node| async move {
                 beacon_node
-                    .get_validator_execution_payload_envelopes_ssz::<S::E>(slot)
+                    .get_validator_execution_payload_envelopes_ssz::<S::E>(slot, beacon_block_root)
                     .await
                     .map_err(|e| {
                         BlockError::Recoverable(format!(
diff --git a/validator_client/validator_store/src/lib.rs b/validator_client/validator_store/src/lib.rs
index d40c7994f11..8c35f5ac0c9 100644
--- a/validator_client/validator_store/src/lib.rs
+++ b/validator_client/validator_store/src/lib.rs
@@ -232,6 +232,20 @@ pub enum UnsignedBlock<E: EthSpec> {
     Blinded(BlindedBeaconBlock<E>),
 }
 
+impl<E: EthSpec> UnsignedBlock<E> {
+    /// The canonical root of this beacon block (identical for the full and blinded forms).
+    ///
+    /// This is the root of the block *this node produced*, which the local beacon node keys its
+    /// pending payload-envelope cache by. It is not necessarily the block ultimately signed or
+    /// published (e.g. under distributed validators).
+    pub fn block_root(&self) -> Hash256 {
+        match self {
+            UnsignedBlock::Full(block) => block.block().canonical_root(),
+            UnsignedBlock::Blinded(block) => block.canonical_root(),
+        }
+    }
+}
+
 #[derive(Clone, Debug, PartialEq)]
 pub enum SignedBlock<E: EthSpec> {
     Full(PublishBlockRequest<E>),