diff --git a/fastapi/sse.py b/fastapi/sse.py
index 7e7ac671c4..37468ff582 100644
--- a/fastapi/sse.py
+++ b/fastapi/sse.py
@@ -43,8 +43,11 @@ def _check_id_no_null_or_newline(v: str | None) -> str | None:
 
 
 def _check_event_no_newline(v: str | None) -> str | None:
-    if v is not None and ("\n" in v or "\r" in v):
-        raise ValueError("SSE 'event' must not contain newline characters")
+    if v is not None:
+        if "\0" in v:
+            raise ValueError("SSE 'event' must not contain null characters")
+        if "\n" in v or "\r" in v:
+            raise ValueError("SSE 'event' must not contain newline characters")
     return v
 
 
@@ -209,7 +212,7 @@ def format_sse_event(
             lines.append(f": {line}")
 
     if event is not None:
-        event = event.replace("\r", "").replace("\n", "")
+        event = event.replace("\r", "").replace("\n", "").replace("\0", "")
         lines.append(f"event: {event}")
 
     if data_str is not None:
diff --git a/tests/test_sse.py b/tests/test_sse.py
index 5f1ae85e37..467c6d8b77 100644
--- a/tests/test_sse.py
+++ b/tests/test_sse.py
@@ -221,6 +221,11 @@ def test_server_sent_event_null_id_rejected():
         ServerSentEvent(data="test", id="has\0null")
 
 
+def test_server_sent_event_null_event_rejected():
+    with pytest.raises(ValueError, match="null"):
+        ServerSentEvent(data="test", event="has\0null")
+
+
 def test_server_sent_event_newline_event_rejected():
     with pytest.raises(ValueError, match="newline"):
         ServerSentEvent(data="test", event="chat\npwned")