diff --git a/codec.go b/codec.go
index d3c2b35bf7e0..e840858b77b1 100644
--- a/codec.go
+++ b/codec.go
@@ -39,17 +39,11 @@ type baseCodec interface {
 // with encoding.GetCodec and if it is registered wraps it with newCodecV1Bridge
 // to turn it into an encoding.CodecV2. Returns nil otherwise.
 func getCodec(name string) encoding.CodecV2 {
-	codecV2 := encoding.GetCodecV2(name)
-	if codecV2 != nil {
-		return codecV2
-	}
-
-	codecV1 := encoding.GetCodec(name)
-	if codecV1 != nil {
+	if codecV1 := encoding.GetCodec(name); codecV1 != nil {
 		return newCodecV1Bridge(codecV1)
 	}
 
-	return nil
+	return encoding.GetCodecV2(name)
 }
 
 func newCodecV0Bridge(c Codec) baseCodec {
diff --git a/codec_test.go b/codec_test.go
index 4e1c625eacc5..f2f88e9636a8 100644
--- a/codec_test.go
+++ b/codec_test.go
@@ -26,7 +26,7 @@ import (
 )
 
 func (s) TestGetCodecForProtoIsNotNil(t *testing.T) {
-	if encoding.GetCodec(proto.Name) == nil {
+	if encoding.GetCodecV2(proto.Name) == nil {
 		t.Fatalf("encoding.GetCodec(%q) must not be nil by default", proto.Name)
 	}
 }
diff --git a/encoding/encoding.go b/encoding/encoding.go
index 5ebf88d7147f..11d0ae142c42 100644
--- a/encoding/encoding.go
+++ b/encoding/encoding.go
@@ -94,7 +94,7 @@ type Codec interface {
 	Name() string
 }
 
-var registeredCodecs = make(map[string]Codec)
+var registeredCodecs = make(map[string]any)
 
 // RegisterCodec registers the provided Codec for use with all gRPC clients and
 // servers.
@@ -126,5 +126,6 @@ func RegisterCodec(codec Codec) {
 //
 // The content-subtype is expected to be lowercase.
 func GetCodec(contentSubtype string) Codec {
-	return registeredCodecs[contentSubtype]
+	c, _ := registeredCodecs[contentSubtype].(Codec)
+	return c
 }
diff --git a/encoding/encoding_test.go b/encoding/encoding_test.go
index 4a4fec33498a..9ac59e461633 100644
--- a/encoding/encoding_test.go
+++ b/encoding/encoding_test.go
@@ -36,6 +36,7 @@ import (
 	"google.golang.org/grpc/internal/grpctest"
 	"google.golang.org/grpc/internal/grpcutil"
 	"google.golang.org/grpc/internal/stubserver"
+	"google.golang.org/grpc/mem"
 	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/status"
 
@@ -90,18 +91,18 @@ type errProtoCodec struct {
 	decodingErr error
 }
 
-func (c *errProtoCodec) Marshal(v any) ([]byte, error) {
+func (c *errProtoCodec) Marshal(v any) (mem.BufferSlice, error) {
 	if c.encodingErr != nil {
 		return nil, c.encodingErr
 	}
-	return encoding.GetCodec(proto.Name).Marshal(v)
+	return encoding.GetCodecV2(proto.Name).Marshal(v)
 }
 
-func (c *errProtoCodec) Unmarshal(data []byte, v any) error {
+func (c *errProtoCodec) Unmarshal(data mem.BufferSlice, v any) error {
 	if c.decodingErr != nil {
 		return c.decodingErr
 	}
-	return encoding.GetCodec(proto.Name).Unmarshal(data, v)
+	return encoding.GetCodecV2(proto.Name).Unmarshal(data, v)
 }
 
 func (c *errProtoCodec) Name() string {
@@ -118,7 +119,7 @@ func (s) TestEncodeDoesntPanicOnServer(t *testing.T) {
 	ec := &errProtoCodec{name: t.Name(), encodingErr: encodingErr}
 
 	// Start a server with the above codec.
-	backend := stubserver.StartTestService(t, nil, grpc.ForceServerCodec(ec))
+	backend := stubserver.StartTestService(t, nil, grpc.ForceServerCodecV2(ec))
 	defer backend.Stop()
 
 	// Create a channel to the above server.
@@ -154,7 +155,7 @@ func (s) TestDecodeDoesntPanicOnServer(t *testing.T) {
 	ec := &errProtoCodec{name: t.Name(), decodingErr: decodingErr}
 
 	// Start a server with the above codec.
-	backend := stubserver.StartTestService(t, nil, grpc.ForceServerCodec(ec))
+	backend := stubserver.StartTestService(t, nil, grpc.ForceServerCodecV2(ec))
 	defer backend.Stop()
 
 	// Create a channel to the above server. Since we do not specify any codec
@@ -206,7 +207,7 @@ func (s) TestEncodeDoesntPanicOnClient(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
 	defer cancel()
 	client := testgrpc.NewTestServiceClient(cc)
-	_, err = client.EmptyCall(ctx, &testpb.Empty{}, grpc.ForceCodec(ec))
+	_, err = client.EmptyCall(ctx, &testpb.Empty{}, grpc.ForceCodecV2(ec))
 	if err == nil || !strings.Contains(err.Error(), encodingErr.Error()) {
 		t.Fatalf("RPC failed with error: %v, want: %v", err, encodingErr)
 	}
@@ -214,7 +215,7 @@ func (s) TestEncodeDoesntPanicOnClient(t *testing.T) {
 	// Configure the codec on the client to not return errors anymore and expect
 	// the RPC to succeed.
 	ec.encodingErr = nil
-	if _, err := client.EmptyCall(ctx, &testpb.Empty{}, grpc.ForceCodec(ec)); err != nil {
+	if _, err := client.EmptyCall(ctx, &testpb.Empty{}, grpc.ForceCodecV2(ec)); err != nil {
 		t.Fatalf("RPC failed with error: %v", err)
 	}
 }
@@ -242,7 +243,7 @@ func (s) TestDecodeDoesntPanicOnClient(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
 	defer cancel()
 	client := testgrpc.NewTestServiceClient(cc)
-	_, err = client.EmptyCall(ctx, &testpb.Empty{}, grpc.ForceCodec(ec))
+	_, err = client.EmptyCall(ctx, &testpb.Empty{}, grpc.ForceCodecV2(ec))
 	if err == nil || !strings.Contains(err.Error(), decodingErr.Error()) {
 		t.Fatalf("RPC failed with error: %v, want: %v", err, decodingErr)
 	}
@@ -250,7 +251,7 @@ func (s) TestDecodeDoesntPanicOnClient(t *testing.T) {
 	// Configure the codec on the client to not return errors anymore and expect
 	// the RPC to succeed.
 	ec.decodingErr = nil
-	if _, err := client.EmptyCall(ctx, &testpb.Empty{}, grpc.ForceCodec(ec)); err != nil {
+	if _, err := client.EmptyCall(ctx, &testpb.Empty{}, grpc.ForceCodecV2(ec)); err != nil {
 		t.Fatalf("RPC failed with error: %v", err)
 	}
 }
@@ -265,14 +266,14 @@ type countingProtoCodec struct {
 	unmarshalCount int32
 }
 
-func (p *countingProtoCodec) Marshal(v any) ([]byte, error) {
+func (p *countingProtoCodec) Marshal(v any) (mem.BufferSlice, error) {
 	atomic.AddInt32(&p.marshalCount, 1)
-	return encoding.GetCodec(proto.Name).Marshal(v)
+	return encoding.GetCodecV2(proto.Name).Marshal(v)
 }
 
-func (p *countingProtoCodec) Unmarshal(data []byte, v any) error {
+func (p *countingProtoCodec) Unmarshal(data mem.BufferSlice, v any) error {
 	atomic.AddInt32(&p.unmarshalCount, 1)
-	return encoding.GetCodec(proto.Name).Unmarshal(data, v)
+	return encoding.GetCodecV2(proto.Name).Unmarshal(data, v)
 }
 
 func (p *countingProtoCodec) Name() string {
@@ -284,7 +285,7 @@ func (p *countingProtoCodec) Name() string {
 func (s) TestForceServerCodec(t *testing.T) {
 	// Create an server with the counting proto codec.
 	codec := &countingProtoCodec{name: t.Name()}
-	backend := stubserver.StartTestService(t, nil, grpc.ForceServerCodec(codec))
+	backend := stubserver.StartTestService(t, nil, grpc.ForceServerCodecV2(codec))
 	defer backend.Stop()
 
 	// Create a channel to the above server.
@@ -317,7 +318,7 @@ func (s) TestForceServerCodec(t *testing.T) {
 
 // renameProtoCodec wraps the proto codec and allows customizing the Name().
 type renameProtoCodec struct {
-	encoding.Codec
+	encoding.CodecV2
 	name string
 }
 
@@ -356,9 +357,9 @@ func (s) TestForceCodecName(t *testing.T) {
 
 	// Force the use of the custom codec on the client with the ForceCodec call
 	// option. Confirm the name is converted to lowercase before transmitting.
-	codec := &renameProtoCodec{Codec: encoding.GetCodec(proto.Name), name: t.Name()}
+	codec := &renameProtoCodec{CodecV2: encoding.GetCodecV2(proto.Name), name: t.Name()}
 	wantContentTypeCh <- []string{fmt.Sprintf("application/grpc+%s", strings.ToLower(t.Name()))}
-	if _, err := ss.Client.EmptyCall(ctx, &testpb.Empty{}, grpc.ForceCodec(codec)); err != nil {
+	if _, err := ss.Client.EmptyCall(ctx, &testpb.Empty{}, grpc.ForceCodecV2(codec)); err != nil {
 		t.Fatalf("ss.Client.EmptyCall(_, _) = _, %v; want _, nil", err)
 	}
 }
diff --git a/encoding/encoding_v2.go b/encoding/encoding_v2.go
index e209f6f1ab62..074c5e234a7b 100644
--- a/encoding/encoding_v2.go
+++ b/encoding/encoding_v2.go
@@ -43,8 +43,6 @@ type CodecV2 interface {
 	Name() string
 }
 
-var registeredV2Codecs = make(map[string]CodecV2)
-
 // RegisterCodecV2 registers the provided CodecV2 for use with all gRPC clients and
 // servers.
 //
@@ -70,7 +68,7 @@ func RegisterCodecV2(codec CodecV2) {
 		panic("cannot register CodecV2 with empty string result for Name()")
 	}
 	contentSubtype := strings.ToLower(codec.Name())
-	registeredV2Codecs[contentSubtype] = codec
+	registeredCodecs[contentSubtype] = codec
 }
 
 // GetCodecV2 gets a registered CodecV2 by content-subtype, or nil if no CodecV2 is
@@ -78,5 +76,6 @@ func RegisterCodecV2(codec CodecV2) {
 //
 // The content-subtype is expected to be lowercase.
 func GetCodecV2(contentSubtype string) CodecV2 {
-	return registeredV2Codecs[contentSubtype]
+	c, _ := registeredCodecs[contentSubtype].(CodecV2)
+	return c
 }
diff --git a/encoding/proto/proto.go b/encoding/proto/proto.go
index 66d5cdf03ec5..ceec319dd2fb 100644
--- a/encoding/proto/proto.go
+++ b/encoding/proto/proto.go
@@ -1,6 +1,6 @@
 /*
  *
- * Copyright 2018 gRPC authors.
+ * Copyright 2024 gRPC authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,6 +24,7 @@ import (
 	"fmt"
 
 	"google.golang.org/grpc/encoding"
+	"google.golang.org/grpc/mem"
 	"google.golang.org/protobuf/proto"
 	"google.golang.org/protobuf/protoadapt"
 )
@@ -32,28 +33,51 @@ import (
 const Name = "proto"
 
 func init() {
-	encoding.RegisterCodec(codec{})
+	encoding.RegisterCodecV2(&codecV2{})
 }
 
-// codec is a Codec implementation with protobuf. It is the default codec for gRPC.
-type codec struct{}
+// codec is a CodecV2 implementation with protobuf. It is the default codec for
+// gRPC.
+type codecV2 struct{}
 
-func (codec) Marshal(v any) ([]byte, error) {
+func (c *codecV2) Marshal(v any) (data mem.BufferSlice, err error) {
 	vv := messageV2Of(v)
 	if vv == nil {
-		return nil, fmt.Errorf("failed to marshal, message is %T, want proto.Message", v)
+		return nil, fmt.Errorf("proto: failed to marshal, message is %T, want proto.Message", v)
 	}
 
-	return proto.Marshal(vv)
+	size := proto.Size(vv)
+	if mem.IsBelowBufferPoolingThreshold(size) {
+		buf, err := proto.Marshal(vv)
+		if err != nil {
+			return nil, err
+		}
+		data = append(data, mem.SliceBuffer(buf))
+	} else {
+		pool := mem.DefaultBufferPool()
+		buf := pool.Get(size)
+		if _, err := (proto.MarshalOptions{}).MarshalAppend((*buf)[:0], vv); err != nil {
+			pool.Put(buf)
+			return nil, err
+		}
+		data = append(data, mem.NewBuffer(buf, pool))
+	}
+
+	return data, nil
 }
 
-func (codec) Unmarshal(data []byte, v any) error {
+func (c *codecV2) Unmarshal(data mem.BufferSlice, v any) (err error) {
 	vv := messageV2Of(v)
 	if vv == nil {
 		return fmt.Errorf("failed to unmarshal, message is %T, want proto.Message", v)
 	}
 
-	return proto.Unmarshal(data, vv)
+	buf := data.MaterializeToBuffer(mem.DefaultBufferPool())
+	defer buf.Free()
+	// TODO: Upgrade proto.Unmarshal to support mem.BufferSlice. Right now, it's not
+	//  really possible without a major overhaul of the proto package, but the
+	//  vtprotobuf library may be able to support this.
+	return proto.Unmarshal(buf.ReadOnlyData(), vv)
 }
 
 func messageV2Of(v any) proto.Message {
@@ -67,6 +91,6 @@ func messageV2Of(v any) proto.Message {
 	return nil
 }
 
-func (codec) Name() string {
+func (c *codecV2) Name() string {
 	return Name
 }
diff --git a/encoding/proto/proto_benchmark_test.go b/encoding/proto/proto_benchmark_test.go
index 8b4cec756342..58007dcbfecc 100644
--- a/encoding/proto/proto_benchmark_test.go
+++ b/encoding/proto/proto_benchmark_test.go
@@ -68,7 +68,7 @@ func BenchmarkProtoCodec(b *testing.B) {
 			protoStructs := setupBenchmarkProtoCodecInputs(s)
 			name := fmt.Sprintf("MinPayloadSize:%v/SetParallelism(%v)", s, p)
 			b.Run(name, func(b *testing.B) {
-				codec := &codec{}
+				codec := &codecV2{}
 				b.SetParallelism(p)
 				b.RunParallel(func(pb *testing.PB) {
 					benchmarkProtoCodec(codec, protoStructs, pb, b)
@@ -78,7 +78,7 @@ func BenchmarkProtoCodec(b *testing.B) {
 	}
 }
 
-func benchmarkProtoCodec(codec *codec, protoStructs []proto.Message, pb *testing.PB, b *testing.B) {
+func benchmarkProtoCodec(codec *codecV2, protoStructs []proto.Message, pb *testing.PB, b *testing.B) {
 	counter := 0
 	for pb.Next() {
 		counter++
@@ -87,7 +87,7 @@ func benchmarkProtoCodec(codec *codec, protoStructs []proto.Message, pb *testing
 	}
 }
 
-func fastMarshalAndUnmarshal(codec encoding.Codec, protoStruct proto.Message, b *testing.B) {
+func fastMarshalAndUnmarshal(codec encoding.CodecV2, protoStruct proto.Message, b *testing.B) {
 	marshaledBytes, err := codec.Marshal(protoStruct)
 	if err != nil {
 		b.Errorf("codec.Marshal(_) returned an error")
diff --git a/encoding/proto/proto_test.go b/encoding/proto/proto_test.go
index d017eb8ec30d..117f3cb97fe8 100644
--- a/encoding/proto/proto_test.go
+++ b/encoding/proto/proto_test.go
@@ -25,10 +25,11 @@ import (
 
 	"google.golang.org/grpc/encoding"
 	"google.golang.org/grpc/internal/grpctest"
+	"google.golang.org/grpc/mem"
 	pb "google.golang.org/grpc/test/codec_perf"
 )
 
-func marshalAndUnmarshal(t *testing.T, codec encoding.Codec, expectedBody []byte) {
+func marshalAndUnmarshal(t *testing.T, codec encoding.CodecV2, expectedBody []byte) {
 	p := &pb.Buffer{}
 	p.Body = expectedBody
 
@@ -55,7 +56,7 @@ func Test(t *testing.T) {
 }
 
 func (s) TestBasicProtoCodecMarshalAndUnmarshal(t *testing.T) {
-	marshalAndUnmarshal(t, codec{}, []byte{1, 2, 3})
+	marshalAndUnmarshal(t, &codecV2{}, []byte{1, 2, 3})
 }
 
 // Try to catch possible race conditions around use of pools
@@ -75,7 +76,7 @@ func (s) TestConcurrentUsage(t *testing.T) {
 	}
 
 	var wg sync.WaitGroup
-	codec := codec{}
+	codec := &codecV2{}
 
 	for i := 0; i < numGoRoutines; i++ {
 		wg.Add(1)
@@ -93,8 +94,8 @@ func (s) TestConcurrentUsage(t *testing.T) {
 // TestStaggeredMarshalAndUnmarshalUsingSamePool tries to catch potential errors in which slices get
 // stomped on during reuse of a proto.Buffer.
 func (s) TestStaggeredMarshalAndUnmarshalUsingSamePool(t *testing.T) {
-	codec1 := codec{}
-	codec2 := codec{}
+	codec1 := &codecV2{}
+	codec2 := &codecV2{}
 
 	expectedBody1 := []byte{1, 2, 3}
 	expectedBody2 := []byte{4, 5, 6}
@@ -102,7 +103,7 @@ func (s) TestStaggeredMarshalAndUnmarshalUsingSamePool(t *testing.T) {
 	proto1 := pb.Buffer{Body: expectedBody1}
 	proto2 := pb.Buffer{Body: expectedBody2}
 
-	var m1, m2 []byte
+	var m1, m2 mem.BufferSlice
 	var err error
 
 	if m1, err = codec1.Marshal(&proto1); err != nil {
diff --git a/encoding/proto/proto_v2.go b/encoding/proto/proto_v2.go
deleted file mode 100644
index 367a3cd66832..000000000000
--- a/encoding/proto/proto_v2.go
+++ /dev/null
@@ -1,81 +0,0 @@
-/*
- *
- * Copyright 2024 gRPC authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- */
-
-package proto
-
-import (
-	"fmt"
-
-	"google.golang.org/grpc/encoding"
-	"google.golang.org/grpc/mem"
-	"google.golang.org/protobuf/proto"
-)
-
-func init() {
-	encoding.RegisterCodecV2(&codecV2{})
-}
-
-// codec is a CodecV2 implementation with protobuf. It is the default codec for
-// gRPC.
-type codecV2 struct{}
-
-var _ encoding.CodecV2 = (*codecV2)(nil)
-
-func (c *codecV2) Marshal(v any) (data mem.BufferSlice, err error) {
-	vv := messageV2Of(v)
-	if vv == nil {
-		return nil, fmt.Errorf("proto: failed to marshal, message is %T, want proto.Message", v)
-	}
-
-	size := proto.Size(vv)
-	if mem.IsBelowBufferPoolingThreshold(size) {
-		buf, err := proto.Marshal(vv)
-		if err != nil {
-			return nil, err
-		}
-		data = append(data, mem.SliceBuffer(buf))
-	} else {
-		pool := mem.DefaultBufferPool()
-		buf := pool.Get(size)
-		if _, err := (proto.MarshalOptions{}).MarshalAppend((*buf)[:0], vv); err != nil {
-			pool.Put(buf)
-			return nil, err
-		}
-		data = append(data, mem.NewBuffer(buf, pool))
-	}
-
-	return data, nil
-}
-
-func (c *codecV2) Unmarshal(data mem.BufferSlice, v any) (err error) {
-	vv := messageV2Of(v)
-	if vv == nil {
-		return fmt.Errorf("failed to unmarshal, message is %T, want proto.Message", v)
-	}
-
-	buf := data.MaterializeToBuffer(mem.DefaultBufferPool())
-	defer buf.Free()
-	// TODO: Upgrade proto.Unmarshal to support mem.BufferSlice. Right now, it's not
-	//  really possible without a major overhaul of the proto package, but the
-	//  vtprotobuf library may be able to support this.
-	return proto.Unmarshal(buf.ReadOnlyData(), vv)
-}
-
-func (c *codecV2) Name() string {
-	return Name
-}