diff --git a/libp2p/transport/webrtc/_varint.py b/libp2p/transport/webrtc/_varint.py
deleted file mode 100644
index 677aef3c9..000000000
--- a/libp2p/transport/webrtc/_varint.py
+++ /dev/null
@@ -1,46 +0,0 @@
-"""
-Unsigned varint encoding for WebRTC data-channel and signaling framing.
-
-Both stream-level data-channel framing and signaling stream framing use the
-same unsigned-varint length-prefix encoding documented in the libp2p
-WebRTC spec.  These sync helpers are shared between modules; for streaming
-async reads see :func:`libp2p.transport.webrtc.signaling._read_uvarint`.
-"""
-
-from __future__ import annotations
-
-# Spec ceiling: a varint encodes at most uint64, which fits in 10 bytes.
-_MAX_VARINT_BYTES = 10
-
-
-def encode_uvarint(value: int) -> bytes:
-    """Encode a non-negative integer as an unsigned varint."""
-    if value < 0:
-        raise ValueError("uvarint cannot encode negative values")
-    buf = bytearray()
-    while value > 0x7F:
-        buf.append((value & 0x7F) | 0x80)
-        value >>= 7
-    buf.append(value & 0x7F)
-    return bytes(buf)
-
-
-def decode_uvarint(data: bytes | bytearray, offset: int = 0) -> tuple[int, int]:
-    """
-    Decode an unsigned varint from *data* starting at *offset*.
-
-    :returns: ``(value, bytes_consumed)``.
-    :raises ValueError: If the varint is truncated or exceeds 10 bytes.
-    """
-    result = 0
-    shift = 0
-    for i in range(_MAX_VARINT_BYTES):
-        pos = offset + i
-        if pos >= len(data):
-            raise ValueError("truncated uvarint")
-        byte = data[pos]
-        result |= (byte & 0x7F) << shift
-        if not (byte & 0x80):
-            return result, i + 1
-        shift += 7
-    raise ValueError(f"uvarint exceeds {_MAX_VARINT_BYTES} bytes")
diff --git a/libp2p/transport/webrtc/signaling.py b/libp2p/transport/webrtc/signaling.py
index f96073739..cab15c78d 100644
--- a/libp2p/transport/webrtc/signaling.py
+++ b/libp2p/transport/webrtc/signaling.py
@@ -32,8 +32,8 @@
 import trio
 
 from libp2p.abc import INetStream
+from libp2p.utils.varint import decode_uvarint_from_stream, encode_uvarint
 
-from ._varint import encode_uvarint
 from .exceptions import WebRTCSignalingError
 from .signaling_pb.signaling_pb2 import SignalingMessage
 
@@ -74,7 +74,7 @@ async def read_signaling_message(stream: INetStream) -> SignalingMessage:
     :raises WebRTCSignalingError: If reading or parsing fails.
     """
     try:
-        length = await _read_uvarint(stream)
+        length = await decode_uvarint_from_stream(stream)
         if length > _MAX_SIGNALING_MSG_SIZE:
             raise WebRTCSignalingError(
                 f"Signaling message too large: {length} bytes "
@@ -261,24 +261,3 @@ async def _receive_expected(self, expected_type: int) -> SignalingMessage:
                 f"Expected signaling message type {expected_type}, got {msg.type}"
             )
         return msg
-
-
-# ------------------------------------------------------------------
-# Streaming varint read (sync encoder/decoder live in ._varint)
-# ------------------------------------------------------------------
-
-
-async def _read_uvarint(stream: INetStream) -> int:
-    """Read an unsigned varint from a libp2p :class:`INetStream`."""
-    result = 0
-    shift = 0
-    for _ in range(10):  # Max 10 bytes for uint64 varint
-        byte_data = await stream.read(1)
-        if not byte_data:
-            raise WebRTCSignalingError("Stream closed while reading varint")
-        byte = byte_data[0]
-        result |= (byte & 0x7F) << shift
-        if not (byte & 0x80):
-            return result
-        shift += 7
-    raise WebRTCSignalingError("Varint too long (> 10 bytes)")
diff --git a/libp2p/transport/webrtc/stream.py b/libp2p/transport/webrtc/stream.py
index e1349f705..61bd3c7e5 100644
--- a/libp2p/transport/webrtc/stream.py
+++ b/libp2p/transport/webrtc/stream.py
@@ -19,8 +19,8 @@
 import trio
 
 from libp2p.abc import IMuxedStream
+from libp2p.utils.varint import decode_varint_with_size, encode_uvarint
 
-from ._varint import decode_uvarint, encode_uvarint
 from .constants import MAX_MESSAGE_SIZE, MAX_PAYLOAD_SIZE
 from .exceptions import WebRTCStreamError
 from .pb.webrtc_pb2 import Message
@@ -301,7 +301,7 @@ def on_data(self, raw: bytes) -> None:
         the mutations inline.
         """
         try:
-            length, consumed = decode_uvarint(raw)
+            length, consumed = decode_varint_with_size(raw)
         except ValueError as e:
             logger.warning(
                 "WebRTCStream channel=%d: malformed varint prefix: %s",
diff --git a/newsfragments/1355.internal.rst b/newsfragments/1355.internal.rst
new file mode 100644
index 000000000..34b47497a
--- /dev/null
+++ b/newsfragments/1355.internal.rst
@@ -0,0 +1 @@
+Removed ``libp2p/transport/webrtc/_varint.py`` and migrated WebRTC stream and signaling framing to use the shared ``libp2p.utils.varint`` utilities (``encode_uvarint``, ``decode_varint_with_size``, ``decode_uvarint_from_stream``), eliminating a duplicate in-tree varint implementation.
diff --git a/tests/core/transport/webrtc/test_connection.py b/tests/core/transport/webrtc/test_connection.py
index d158d7e6a..d7e71cf37 100644
--- a/tests/core/transport/webrtc/test_connection.py
+++ b/tests/core/transport/webrtc/test_connection.py
@@ -124,8 +124,8 @@ class TestMessageRouting:
     async def test_on_channel_message_routes_to_stream(self):
         conn = _make_connection()
         stream = await conn.open_stream()
-        from libp2p.transport.webrtc._varint import encode_uvarint
         from libp2p.transport.webrtc.pb.webrtc_pb2 import Message
+        from libp2p.utils.varint import encode_uvarint
 
         proto = Message(message=b"test-data").SerializeToString()
         framed = encode_uvarint(len(proto)) + proto
diff --git a/tests/core/transport/webrtc/test_signaling.py b/tests/core/transport/webrtc/test_signaling.py
index ee1df1e3f..3f7962be7 100644
--- a/tests/core/transport/webrtc/test_signaling.py
+++ b/tests/core/transport/webrtc/test_signaling.py
@@ -13,14 +13,16 @@
 import pytest
 import trio
 
-from libp2p.transport.webrtc._varint import encode_uvarint as _encode_uvarint
 from libp2p.transport.webrtc.signaling import (
     SignalingSession,
-    _read_uvarint,
     read_signaling_message,
     write_signaling_message,
 )
 from libp2p.transport.webrtc.signaling_pb.signaling_pb2 import SignalingMessage
+from libp2p.utils.varint import (
+    decode_uvarint_from_stream as _read_uvarint,
+    encode_uvarint as _encode_uvarint,
+)
 
 
 class MockStream:
diff --git a/tests/core/transport/webrtc/test_stream.py b/tests/core/transport/webrtc/test_stream.py
index 40657596f..bb58a89b2 100644
--- a/tests/core/transport/webrtc/test_stream.py
+++ b/tests/core/transport/webrtc/test_stream.py
@@ -9,10 +9,10 @@
 
 import pytest
 
-from libp2p.transport.webrtc._varint import decode_uvarint, encode_uvarint
 from libp2p.transport.webrtc.constants import MAX_PAYLOAD_SIZE
 from libp2p.transport.webrtc.pb.webrtc_pb2 import Message
 from libp2p.transport.webrtc.stream import StreamState, WebRTCStream
+from libp2p.utils.varint import decode_varint_with_size, encode_uvarint
 
 
 def _framed(msg: Message) -> bytes:
@@ -23,7 +23,7 @@ def _framed(msg: Message) -> bytes:
 
 def _parse_framed(raw: bytes) -> Message:
     """Inverse of :func:`_framed` — decode the wire format back to a Message."""
-    length, consumed = decode_uvarint(raw)
+    length, consumed = decode_varint_with_size(raw)
     msg = Message()
     msg.ParseFromString(raw[consumed : consumed + length])
     return msg