diff --git a/src/pytest_reportlog/plugin.py b/src/pytest_reportlog/plugin.py
index d44d56f..1f00a68 100644
--- a/src/pytest_reportlog/plugin.py
+++ b/src/pytest_reportlog/plugin.py
@@ -1,10 +1,25 @@
 import json
+import re
 from typing import Dict, Any, TextIO
 
 from _pytest.pathlib import Path
 
 import pytest
 
+_ANSI_ESCAPE_RE = re.compile(r"\x1b(?:[@-Z\\-_]|\[[0-?]*[ -/]*[@-~])")
+
+
+def _strip_ansi(obj: Any) -> Any:
+    if isinstance(obj, str):
+        return _ANSI_ESCAPE_RE.sub("", obj)
+    if isinstance(obj, dict):
+        return {_strip_ansi(k): _strip_ansi(v) for k, v in obj.items()}
+    if isinstance(obj, list):
+        return [_strip_ansi(v) for v in obj]
+    if isinstance(obj, tuple):
+        return tuple(_strip_ansi(v) for v in obj)
+    return obj
+
 
 def pytest_addoption(parser):
     group = parser.getgroup("terminal reporting", "report-log plugin options")
@@ -69,10 +84,12 @@ def close(self):
             self._file = None
 
     def _write_json_data(self, data):
+        data = _strip_ansi(data)
         try:
             json_data = json.dumps(data)
         except TypeError:
             data = cleanup_unserializable(data)
+            data = _strip_ansi(data)
             json_data = json.dumps(data)
         self._file.write(json_data + "\n")
         self._file.flush()
diff --git a/tests/test_reportlog.py b/tests/test_reportlog.py
index 032df8b..258877e 100644
--- a/tests/test_reportlog.py
+++ b/tests/test_reportlog.py
@@ -184,6 +184,7 @@ def __str__(self):
 
 def test_subtest(pytester, tmp_path):
     """Regression test for #90."""
+    pytest.importorskip("pytest_subtests")
     pytester.makepyfile("""
         def test_foo(subtests):
             with subtests.test():
@@ -196,3 +197,31 @@ def test_foo(subtests):
     for line in lines:
         data = json.loads(line)
         assert "$report_type" in data
+
+
+def _contains_ansi_escape(obj) -> bool:
+    if isinstance(obj, str):
+        return "\x1b" in obj
+    if isinstance(obj, dict):
+        return any(
+            _contains_ansi_escape(k) or _contains_ansi_escape(v) for k, v in obj.items()
+        )
+    if isinstance(obj, (list, tuple)):
+        return any(_contains_ansi_escape(v) for v in obj)
+    return False
+
+
+def test_strips_ansi_escape_sequences(testdir, tmp_path):
+    testdir.makepyfile(r"""
+        import pytest
+
+        def test_fail_with_ansi_message():
+            pytest.fail("\x1b[31mRED\x1b[0m")
+        """)
+    fn = tmp_path / "result.log"
+    result = testdir.runpytest(f"--report-log={fn}")
+    assert result.ret == pytest.ExitCode.TESTS_FAILED
+
+    for line in fn.read_text("UTF-8").splitlines():
+        data = json.loads(line)
+        assert not _contains_ansi_escape(data)