diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4c32f696a..b73d51298 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ This changelog is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.
 
 ### Added
 - Codecov workflow
+- Added unit tests for `key_format.py` to improve coverage.
 - Fix inactivity bot execution for local dry-run testing.
 - Added documentation: "Testing GitHub Actions using Forks" (`docs/sdk_developers/training/testing_forks.md`).
 - Unified the inactivity-unassign bot into a single script with `DRY_RUN` support, and fixed handling of cross-repo PR references for stale detection.
diff --git a/tests/unit/test_key_format.py b/tests/unit/test_key_format.py
new file mode 100644
index 000000000..b11d5c98b
--- /dev/null
+++ b/tests/unit/test_key_format.py
@@ -0,0 +1,73 @@
+"""Tests for the key_format module."""
+
+import pytest
+
+from hiero_sdk_python.crypto.private_key import PrivateKey
+from hiero_sdk_python.hapi.services import basic_types_pb2
+from hiero_sdk_python.utils.key_utils import key_to_proto
+from hiero_sdk_python.utils.key_format import format_key
+
+pytestmark = pytest.mark.unit
+
+def test_format_key_ed25519():
+    """Test formatting an Ed25519 key."""
+    private_key = PrivateKey.generate_ed25519()
+    public_key = private_key.public_key()
+
+    proto_key = key_to_proto(public_key)
+    formatted = format_key(proto_key)
+
+    expected = f"ed25519({public_key.to_bytes_raw().hex()})"
+
+    assert formatted == expected
+
+def test_format_key_none():
+    """Test formatting a None key."""
+    formatted = format_key(None)
+
+    assert formatted == "None" 
+
+def test_format_key_threshold_key():
+    """Test formatting a ThresholdKey."""
+
+    key = basic_types_pb2.Key()
+    key.thresholdKey.threshold = 2
+
+    formatted = format_key(key)
+
+    assert formatted == "thresholdKey(...)"
+
+def test_format_key_contract_id():
+    """Test formatting a ContractID key."""
+
+    key = basic_types_pb2.Key()
+    key.contractID.shardNum = 0
+    key.contractID.realmNum = 0
+    key.contractID.contractNum = 5678
+
+    expected_inner = str(key.contractID) 
+    expected = f"contractID({expected_inner})"
+
+    formatted = format_key(key)
+
+    assert formatted == expected
+
+def test_format_key_keylist():
+    """Test formatting a KeyList."""
+
+    key = basic_types_pb2.Key()
+    key.keyList.keys.add()
+
+    formatted = format_key(key)
+
+    assert formatted == "keyList(...)"
+
+def test_format_key_unknown():
+    """Test formatting an unknown key type."""
+    key = basic_types_pb2.Key()
+    # Intentionally not setting any known key type
+
+    formatted = format_key(key)
+    expected = str(key).replace("\n", " ")
+
+    assert formatted == expected
\ No newline at end of file