diff --git a/singer_sdk/_singerlib/encoding/_msgspec.py b/singer_sdk/_singerlib/encoding/_msgspec.py
index ed8a9f836..979d41fe3 100644
--- a/singer_sdk/_singerlib/encoding/_msgspec.py
+++ b/singer_sdk/_singerlib/encoding/_msgspec.py
@@ -43,6 +43,22 @@ def dec_hook(type: type, obj: t.Any) -> t.Any:  # noqa: ARG001, A002, ANN401
 
 encoder = msgspec.json.Encoder(enc_hook=enc_hook, decimal_format="number")
 decoder = msgspec.json.Decoder(dec_hook=dec_hook, float_hook=decimal.Decimal)
+_jsonl_msg_buffer = bytearray(64)
+
+
+def serialize_jsonl(obj: object, **kwargs: t.Any) -> bytes:  # noqa: ARG001
+    """Serialize a dictionary into a line of jsonl.
+
+    Args:
+        obj: A Python object usually a dict.
+        **kwargs: Optional key word arguments.
+
+    Returns:
+        A bytes of serialized json.
+    """
+    encoder.encode_into(obj, _jsonl_msg_buffer)
+    _jsonl_msg_buffer.extend(b"\n")
+    return _jsonl_msg_buffer
 
 
 class MsgSpecReader(GenericSingerReader[str]):
@@ -82,7 +98,7 @@ def serialize_message(self, message: Message) -> bytes:  # noqa: PLR6301
         Returns:
             A string of serialized json.
         """
-        return encoder.encode(message.to_dict())
+        return serialize_jsonl(message.to_dict())
 
     def write_message(self, message: Message) -> None:
         """Write a message to stdout.
@@ -90,5 +106,5 @@ def write_message(self, message: Message) -> None:
         Args:
             message: The message to write.
         """
-        sys.stdout.buffer.write(self.format_message(message) + b"\n")
+        sys.stdout.buffer.write(self.format_message(message))
         sys.stdout.flush()