diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go
index 20dceba74b..17b13016ca 100644
--- a/internal/ethapi/api.go
+++ b/internal/ethapi/api.go
@@ -1869,6 +1869,8 @@ type SignTransactionResult struct {
 // The node needs to have the private key of the account corresponding with
 // the given from address and it needs to be unlocked.
 func (s *TransactionAPI) SignTransaction(ctx context.Context, args TransactionArgs) (*SignTransactionResult, error) {
+	args.blobSidecarAllowed = true
+
 	if args.Gas == nil {
 		return nil, errors.New("gas not specified")
 	}
diff --git a/signer/core/api.go b/signer/core/api.go
index a32f24cb18..23ddcd0a20 100644
--- a/signer/core/api.go
+++ b/signer/core/api.go
@@ -590,7 +590,10 @@ func (api *SignerAPI) SignTransaction(ctx context.Context, args apitypes.SendTxA
 		return nil, err
 	}
 	// Convert fields into a real transaction
-	var unsignedTx = result.Transaction.ToTransaction()
+	unsignedTx, err := result.Transaction.ToTransaction()
+	if err != nil {
+		return nil, err
+	}
 	// Get the password for the transaction
 	pw, err := api.lookupOrQueryPassword(acc.Address, "Account password",
 		fmt.Sprintf("Please enter the password for account %s", acc.Address.String()))
diff --git a/signer/core/apitypes/types.go b/signer/core/apitypes/types.go
index a0c89e3efd..635e3f4532 100644
--- a/signer/core/apitypes/types.go
+++ b/signer/core/apitypes/types.go
@@ -28,6 +28,7 @@ import (
 	"strconv"
 	"strings"
 
+	"crypto/sha256"
 	"github.com/ethereum/go-ethereum/accounts"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
@@ -131,14 +132,16 @@ func (args *SendTxArgs) data() []byte {
 }
 
 // ToTransaction converts the arguments to a transaction.
-func (args *SendTxArgs) ToTransaction() *types.Transaction {
+func (args *SendTxArgs) ToTransaction() (*types.Transaction, error) {
 	// Add the To-field, if specified
 	var to *common.Address
 	if args.To != nil {
 		dstAddr := args.To.Address()
 		to = &dstAddr
 	}
-
+	if err := args.validateTxSidecar(); err != nil {
+		return nil, err
+	}
 	var data types.TxData
 	switch {
 	case args.BlobHashes != nil:
@@ -204,7 +207,78 @@ func (args *SendTxArgs) ToTransaction() *types.Transaction {
 			Data:     args.data(),
 		}
 	}
-	return types.NewTx(data)
+
+	return types.NewTx(data), nil
+}
+
+// validateTxSidecar validates blob data, if present
+func (args *SendTxArgs) validateTxSidecar() error {
+	// No blobs, we're done.
+	if args.Blobs == nil {
+		return nil
+	}
+
+	n := len(args.Blobs)
+	// Assume user provides either only blobs (w/o hashes), or
+	// blobs together with commitments and proofs.
+	if args.Commitments == nil && args.Proofs != nil {
+		return errors.New(`blob proofs provided while commitments were not`)
+	} else if args.Commitments != nil && args.Proofs == nil {
+		return errors.New(`blob commitments provided while proofs were not`)
+	}
+
+	// len(blobs) == len(commitments) == len(proofs) == len(hashes)
+	if args.Commitments != nil && len(args.Commitments) != n {
+		return fmt.Errorf("number of blobs and commitments mismatch (have=%d, want=%d)", len(args.Commitments), n)
+	}
+	if args.Proofs != nil && len(args.Proofs) != n {
+		return fmt.Errorf("number of blobs and proofs mismatch (have=%d, want=%d)", len(args.Proofs), n)
+	}
+	if args.BlobHashes != nil && len(args.BlobHashes) != n {
+		return fmt.Errorf("number of blobs and hashes mismatch (have=%d, want=%d)", len(args.BlobHashes), n)
+	}
+
+	if args.Commitments == nil {
+		// Generate commitment and proof.
+		commitments := make([]kzg4844.Commitment, n)
+		proofs := make([]kzg4844.Proof, n)
+		for i, b := range args.Blobs {
+			c, err := kzg4844.BlobToCommitment(b)
+			if err != nil {
+				return fmt.Errorf("blobs[%d]: error computing commitment: %v", i, err)
+			}
+			commitments[i] = c
+			p, err := kzg4844.ComputeBlobProof(b, c)
+			if err != nil {
+				return fmt.Errorf("blobs[%d]: error computing proof: %v", i, err)
+			}
+			proofs[i] = p
+		}
+		args.Commitments = commitments
+		args.Proofs = proofs
+	} else {
+		for i, b := range args.Blobs {
+			if err := kzg4844.VerifyBlobProof(b, args.Commitments[i], args.Proofs[i]); err != nil {
+				return fmt.Errorf("failed to verify blob proof: %v", err)
+			}
+		}
+	}
+
+	hashes := make([]common.Hash, n)
+	hasher := sha256.New()
+	for i, c := range args.Commitments {
+		hashes[i] = kzg4844.CalcBlobHashV1(hasher, &c)
+	}
+	if args.BlobHashes != nil {
+		for i, h := range hashes {
+			if h != args.BlobHashes[i] {
+				return fmt.Errorf("blob hash verification failed (have=%s, want=%s)", args.BlobHashes[i], h)
+			}
+		}
+	} else {
+		args.BlobHashes = hashes
+	}
+	return nil
 }
 
 type SigFormat struct {
diff --git a/signer/core/apitypes/types_test.go b/signer/core/apitypes/types_test.go
index fc9341da6e..761b2ef5af 100644
--- a/signer/core/apitypes/types_test.go
+++ b/signer/core/apitypes/types_test.go
@@ -20,8 +20,11 @@ import (
 	"encoding/json"
 	"testing"
 
+	"crypto/sha256"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto/kzg4844"
+	"github.com/holiman/uint256"
 )
 
 func TestIsPrimitive(t *testing.T) {
@@ -83,7 +86,9 @@ func TestTxArgs(t *testing.T) {
 		if err := json.Unmarshal(d2, &txArgs2); err != nil {
 			t.Fatal(err)
 		}
-		if have, want := txArgs.ToTransaction().Hash(), txArgs2.ToTransaction().Hash(); have != want {
+		tx1, _ := txArgs.ToTransaction()
+		tx2, _ := txArgs2.ToTransaction()
+		if have, want := tx1.Hash(), tx2.Hash(); have != want {
 			t.Errorf("test %d: have %v, want %v", i, have, want)
 		}
 	}
@@ -98,3 +103,39 @@ func TestTxArgs(t *testing.T) {
 				> eth.signTransaction(tx)
 	*/
 }
+
+func TestBlobTxs(t *testing.T) {
+	blob := kzg4844.Blob{0x1}
+	committment, err := kzg4844.BlobToCommitment(blob)
+	if err != nil {
+		t.Fatal(err)
+	}
+	proof, err := kzg4844.ComputeBlobProof(blob, committment)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	hash := kzg4844.CalcBlobHashV1(sha256.New(), &committment)
+	b := &types.BlobTx{
+		ChainID:    uint256.NewInt(6),
+		Nonce:      8,
+		GasTipCap:  uint256.NewInt(500),
+		GasFeeCap:  uint256.NewInt(600),
+		Gas:        21000,
+		BlobFeeCap: uint256.NewInt(700),
+		BlobHashes: []common.Hash{hash},
+		Value:      uint256.NewInt(100),
+		Sidecar: &types.BlobTxSidecar{
+			Blobs:       []kzg4844.Blob{blob},
+			Commitments: []kzg4844.Commitment{committment},
+			Proofs:      []kzg4844.Proof{proof},
+		},
+	}
+	tx := types.NewTx(b)
+	data, err := json.Marshal(tx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("tx %v", string(data))
+
+}
diff --git a/signer/core/cliui.go b/signer/core/cliui.go
index b1bd3206ed..e04077865d 100644
--- a/signer/core/cliui.go
+++ b/signer/core/cliui.go
@@ -128,7 +128,7 @@ func (ui *CommandlineUI) ApproveTx(request *SignTxRequest) (SignTxResponse, erro
 		fmt.Printf("chainid:  %v\n", chainId)
 	}
 	if list := request.Transaction.AccessList; list != nil {
-		fmt.Printf("Accesslist\n")
+		fmt.Printf("Accesslist:\n")
 		for i, el := range *list {
 			fmt.Printf(" %d. %v\n", i, el.Address)
 			for j, slot := range el.StorageKeys {
@@ -136,6 +136,12 @@ func (ui *CommandlineUI) ApproveTx(request *SignTxRequest) (SignTxResponse, erro
 			}
 		}
 	}
+	if len(request.Transaction.BlobHashes) > 0 {
+		fmt.Printf("Blob hashes:\n")
+		for _, bh := range request.Transaction.BlobHashes {
+			fmt.Printf("   %v\n", bh)
+		}
+	}
 	if request.Transaction.Data != nil {
 		d := *request.Transaction.Data
 		if len(d) > 0 {
diff --git a/signer/fourbyte/validation.go b/signer/fourbyte/validation.go
index 58111e8e00..0451bda91d 100644
--- a/signer/fourbyte/validation.go
+++ b/signer/fourbyte/validation.go
@@ -36,6 +36,11 @@ func (db *Database) ValidateTransaction(selector *string, tx *apitypes.SendTxArg
 	if tx.Data != nil && tx.Input != nil && !bytes.Equal(*tx.Data, *tx.Input) {
 		return nil, errors.New(`ambiguous request: both "data" and "input" are set and are not identical`)
 	}
+	// ToTransaction validates, among other things, that blob hashes match with blobs, and also
+	// populates the hashes if they were previously unset.
+	if _, err := tx.ToTransaction(); err != nil {
+		return nil, err
+	}
 	// Place data on 'data', and nil 'input'
 	var data []byte
 	if tx.Input != nil {