diff --git a/src/lightning/pytorch/CHANGELOG.md b/src/lightning/pytorch/CHANGELOG.md
index 1c7aa467bff01..6ab5a2223cd59 100644
--- a/src/lightning/pytorch/CHANGELOG.md
+++ b/src/lightning/pytorch/CHANGELOG.md
@@ -56,6 +56,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Fixed `ModelCheckpoint` not expanding the `dirpath` if it has the `~` (home) prefix ([#19058](https://github.com/Lightning-AI/lightning/pull/19058))
 
 
+- Fixed handling checkpoint dirpath suffix in NeptuneLogger ([#18863](https://github.com/Lightning-AI/lightning/pull/18863))
+
+
 
 ## [2.1.2] - 2023-11-15
 
diff --git a/src/lightning/pytorch/loggers/neptune.py b/src/lightning/pytorch/loggers/neptune.py
index d8f8b36251c7f..6e8d268dff95a 100644
--- a/src/lightning/pytorch/loggers/neptune.py
+++ b/src/lightning/pytorch/loggers/neptune.py
@@ -557,13 +557,14 @@ def after_save_checkpoint(self, checkpoint_callback: Checkpoint) -> None:
     def _get_full_model_name(model_path: str, checkpoint_callback: Checkpoint) -> str:
         """Returns model name which is string `model_path` appended to `checkpoint_callback.dirpath`."""
         if hasattr(checkpoint_callback, "dirpath"):
-            expected_model_path = f"{checkpoint_callback.dirpath}{os.path.sep}"
+            model_path = os.path.normpath(model_path)
+            expected_model_path = os.path.normpath(checkpoint_callback.dirpath)
             if not model_path.startswith(expected_model_path):
                 raise ValueError(f"{model_path} was expected to start with {expected_model_path}.")
             # Remove extension from filepath
-            filepath, _ = os.path.splitext(model_path[len(expected_model_path) :])
-            return filepath
-        return model_path
+            filepath, _ = os.path.splitext(model_path[len(expected_model_path) + 1 :])
+            return filepath.replace(os.sep, "/")
+        return model_path.replace(os.sep, "/")
 
     @classmethod
     def _get_full_model_names_from_exp_structure(cls, exp_structure: Dict[str, Any], namespace: str) -> Set[str]:
diff --git a/tests/tests_pytorch/loggers/test_neptune.py b/tests/tests_pytorch/loggers/test_neptune.py
index 90f162f8c2564..9065a48478da7 100644
--- a/tests/tests_pytorch/loggers/test_neptune.py
+++ b/tests/tests_pytorch/loggers/test_neptune.py
@@ -284,10 +284,12 @@ def test_get_full_model_name():
             os.path.join("foo", "bar", "key/in/parts.ext"),
             SimpleCheckpoint(dirpath=os.path.join("foo", "bar")),
         ),
+        ("key", os.path.join("../foo", "bar", "key.ext"), SimpleCheckpoint(dirpath=os.path.join("../foo", "bar"))),
+        ("key", os.path.join("foo", "key.ext"), SimpleCheckpoint(dirpath=os.path.join("./foo", "bar/../"))),
     ]
 
-    for expected_model_name, *key_and_path in test_input_data:
-        assert NeptuneLogger._get_full_model_name(*key_and_path) == expected_model_name
+    for expected_model_name, model_path, checkpoint in test_input_data:
+        assert NeptuneLogger._get_full_model_name(model_path, checkpoint) == expected_model_name
 
 
 def test_get_full_model_names_from_exp_structure():