diff --git a/AllTests-mainnet.md b/AllTests-mainnet.md
index 3dd522f11..53e50809f 100644
--- a/AllTests-mainnet.md
+++ b/AllTests-mainnet.md
@@ -350,6 +350,7 @@ OK: 4/4 Fail: 0/4 Skip: 0/4
 ```diff
 + Aggregate and proof signatures                                                             OK
 + Attestation signatures                                                                     OK
++ Blob sidecar signatures                                                                    OK
 + Deposit signatures                                                                         OK
 + Slot signatures                                                                            OK
 + Sync committee message signatures                                                          OK
@@ -357,7 +358,7 @@ OK: 4/4 Fail: 0/4 Skip: 0/4
 + Sync committee signed contribution and proof signatures                                    OK
 + Voluntary exit signatures                                                                  OK
 ```
-OK: 8/8 Fail: 0/8 Skip: 0/8
+OK: 9/9 Fail: 0/9 Skip: 0/9
 ## Network metadata
 ```diff
 + goerli                                                                                     OK
@@ -690,4 +691,4 @@ OK: 2/2 Fail: 0/2 Skip: 0/2
 OK: 9/9 Fail: 0/9 Skip: 0/9
 
 ---TOTAL---
-OK: 391/396 Fail: 0/396 Skip: 5/396
+OK: 392/397 Fail: 0/397 Skip: 5/397
diff --git a/beacon_chain/spec/signatures.nim b/beacon_chain/spec/signatures.nim
index 0759f5296..d3ea558ac 100644
--- a/beacon_chain/spec/signatures.nim
+++ b/beacon_chain/spec/signatures.nim
@@ -107,6 +107,15 @@ func get_block_signature*(
 
   blsSign(privkey, signing_root.data)
 
+# https://github.com/ethereum/consensus-specs/blob/v1.4.0-alpha.3/specs/deneb/validator.md#constructing-the-signedblobsidecars
+proc get_blob_sidecar_signature*(
+  fork: Fork, genesis_validators_root: Eth2Digest, slot: Slot,
+    blob: BlobSidecar, privkey: ValidatorPrivKey): CookedSig =
+  let signing_root = compute_blob_signing_root(
+    fork, genesis_validators_root, slot, blob)
+
+  blsSign(privkey, signing_root.data)
+
 proc verify_block_signature*(
     fork: Fork, genesis_validators_root: Eth2Digest, slot: Slot,
     blck: Eth2Digest | SomeForkyBeaconBlock | BeaconBlockHeader,
diff --git a/beacon_chain/validators/validator_pool.nim b/beacon_chain/validators/validator_pool.nim
index 3cdb080ac..0eee9de4a 100644
--- a/beacon_chain/validators/validator_pool.nim
+++ b/beacon_chain/validators/validator_pool.nim
@@ -615,6 +615,20 @@ proc getBlockSignature*(v: AttachedValidator, fork: Fork,
                 proofs)
       await v.signData(web3SignerRequest)
 
+# https://github.com/ethereum/consensus-specs/blob/v1.4.0-alpha.3/specs/deneb/validator.md#constructing-the-signedblobsidecars
+proc getBlobSignature*(v: AttachedValidator, fork: Fork,
+                       genesis_validators_root: Eth2Digest, slot: Slot,
+                       blob: BlobSidecar): Future[SignatureResult] {.async.} =
+  return
+    case v.kind
+    of ValidatorKind.Local:
+      SignatureResult.ok(
+        get_blob_sidecar_signature(
+          fork, genesis_validators_root, slot, blob,
+          v.data.privateKey).toValidatorSig())
+    of ValidatorKind.Remote:
+      return SignatureResult.err("web3signer not supported for blobs")
+
 # https://github.com/ethereum/consensus-specs/blob/v1.3.0/specs/phase0/validator.md#aggregate-signature
 proc getAttestationSignature*(v: AttachedValidator, fork: Fork,
                               genesis_validators_root: Eth2Digest,
diff --git a/tests/test_message_signatures.nim b/tests/test_message_signatures.nim
index b815c761f..886690aec 100644
--- a/tests/test_message_signatures.nim
+++ b/tests/test_message_signatures.nim
@@ -1,5 +1,5 @@
 # beacon_chain
-# Copyright (c) 2018-2021 Status Research & Development GmbH
+# Copyright (c) 2018-2023 Status Research & Development GmbH
 # Licensed and distributed under either of
 #   * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
 #   * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
@@ -58,6 +58,36 @@ suite "Message signatures":
         get_block_signature(
           fork0, genesis_validators_root1, slot, root, privkey0).toValidatorSig)
 
+  test "Blob sidecar signatures":
+    let
+      slot = default(Slot)
+      blob = default(BlobSidecar)
+
+    check:
+      # Matching public/private keys and genesis validator roots
+      verify_blob_signature(
+        fork0, genesis_validators_root0, slot, blob, pubkey0,
+        get_blob_sidecar_signature(
+          fork0, genesis_validators_root0, slot, blob, privkey0).toValidatorSig)
+
+      # Mismatched public/private keys
+      not verify_blob_signature(
+        fork0, genesis_validators_root0, slot, blob, pubkey0,
+        get_blob_sidecar_signature(
+          fork0, genesis_validators_root0, slot, blob, privkey1).toValidatorSig)
+
+      # Mismatched forks
+      not verify_blob_signature(
+        fork0, genesis_validators_root0, slot, blob, pubkey0,
+        get_blob_sidecar_signature(
+          fork1, genesis_validators_root0, slot, blob, privkey0).toValidatorSig)
+
+      # Mismatched genesis validator roots
+      not verify_blob_signature(
+        fork0, genesis_validators_root0, slot, blob, pubkey0,
+        get_blob_sidecar_signature(
+          fork0, genesis_validators_root1, slot, blob, privkey0).toValidatorSig)
+
   test "Aggregate and proof signatures":
     let aggregate_and_proof = AggregateAndProof(
       aggregate: Attestation(aggregation_bits: CommitteeValidatorsBits.init(8)))