diff --git a/AUTHORS b/AUTHORS
index b59ebc2a2..68f156862 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -216,6 +216,7 @@ Ondřej Súkup
 Oscar Benjamin
 Patrick Hayes
 Pauli Virtanen
+Pavel Karateev
 Paweł Adamczak
 Pedro Algarvio
 Philipp Loose
diff --git a/changelog/7126.bugfix.rst b/changelog/7126.bugfix.rst
new file mode 100644
index 000000000..6817ee211
--- /dev/null
+++ b/changelog/7126.bugfix.rst
@@ -0,0 +1,3 @@
+Use ``saferepr`` to format bytes ``parametrize`` parameters  for ``--setup-show``
+output to prevent errors when Python is called with ``-bb`` to catch bytearray with
+unicode comparison.
diff --git a/src/_pytest/setuponly.py b/src/_pytest/setuponly.py
index c9cc589ff..e18208e59 100644
--- a/src/_pytest/setuponly.py
+++ b/src/_pytest/setuponly.py
@@ -1,4 +1,5 @@
 import pytest
+from _pytest._io.saferepr import saferepr
 
 
 def pytest_addoption(parser):
@@ -66,7 +67,11 @@ def _show_fixture_action(fixturedef, msg):
             tw.write(" (fixtures used: {})".format(", ".join(deps)))
 
     if hasattr(fixturedef, "cached_param"):
-        tw.write("[{}]".format(fixturedef.cached_param))
+        if isinstance(fixturedef.cached_param, bytes):
+            param = saferepr(fixturedef.cached_param, maxsize=42)
+        else:
+            param = fixturedef.cached_param
+        tw.write("[{}]".format(param))
 
     tw.flush()
 
diff --git a/testing/test_setuponly.py b/testing/test_setuponly.py
index e26a33dee..779c17fbd 100644
--- a/testing/test_setuponly.py
+++ b/testing/test_setuponly.py
@@ -1,3 +1,5 @@
+import sys
+
 import pytest
 from _pytest.config import ExitCode
 
@@ -292,3 +294,19 @@ def test_setup_show_with_KeyboardInterrupt_in_test(testdir):
         ]
     )
     assert result.ret == ExitCode.INTERRUPTED
+
+
+def test_parametrize_no_comparing_bytearray_error(testdir):
+    test_file = testdir.makepyfile(
+        """
+        import pytest
+
+        @pytest.mark.parametrize('data', [b'Hello World'])
+        def test_data(data):
+            pass
+        """
+    )
+    result = testdir.run(
+        sys.executable, "-bb", "-m", "pytest", "--setup-show", str(test_file)
+    )
+    assert result.ret == 0