diff --git a/.gitignore b/.gitignore
index db35ac44c6207..fff549a718794 100644
--- a/.gitignore
+++ b/.gitignore
@@ -138,3 +138,4 @@ mlruns/
 *.ckpt
 pytorch\ lightning
 test-reports/
+wandb
diff --git a/CHANGELOG.md b/CHANGELOG.md
index cc7ec0401d93c..9a534c6bfaf40 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,28 +11,44 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 
 - Added `dirpath` and `filename` parameter in `ModelCheckpoint` ([#4213](https://github.com/PyTorchLightning/pytorch-lightning/pull/4213))
 
+
 - Added plugins docs and DDPPlugin to customize ddp across all accelerators([#4258](https://github.com/PyTorchLightning/pytorch-lightning/pull/4285))
 
+
 - Added `strict` option to the scheduler dictionary ([#3586](https://github.com/PyTorchLightning/pytorch-lightning/pull/3586))
 
+
 - Added `fsspec` support for profilers ([#4162](https://github.com/PyTorchLightning/pytorch-lightning/pull/4162))
 
+
 ### Changed
 
+
 - Improved error messages for invalid `configure_optimizers` returns ([#3587](https://github.com/PyTorchLightning/pytorch-lightning/pull/3587))
 
+
 - Allow changing the logged step value in `validation_step` ([#4130](https://github.com/PyTorchLightning/pytorch-lightning/pull/4130))
+
+
 - Allow setting `replace_sampler_ddp=True` with a distributed sampler already added ([#4273](https://github.com/PyTorchLightning/pytorch-lightning/pull/4273))
 
+
+- Fixed santized parameters for `WandbLogger.log_hyperparams` ([#4320](https://github.com/PyTorchLightning/pytorch-lightning/pull/4320))
+
+
 ### Deprecated
 
+
 - Deprecated `filepath` in `ModelCheckpoint` ([#4213](https://github.com/PyTorchLightning/pytorch-lightning/pull/4213))
 
+
 - Deprecated `reorder` parameter of the `auc` metric ([#4237](https://github.com/PyTorchLightning/pytorch-lightning/pull/4237))
 
+
 ### Removed
 
 
+
 ### Fixed
 
 - Fixed setting device ids in DDP ([#4297](https://github.com/PyTorchLightning/pytorch-lightning/pull/4297))
diff --git a/pytorch_lightning/loggers/base.py b/pytorch_lightning/loggers/base.py
index 8f72830027806..cf0b22d7d446f 100644
--- a/pytorch_lightning/loggers/base.py
+++ b/pytorch_lightning/loggers/base.py
@@ -168,6 +168,31 @@ def _convert_params(params: Union[Dict[str, Any], Namespace]) -> Dict[str, Any]:
 
         return params
 
+    @staticmethod
+    def _sanitize_callable_params(params: Dict[str, Any]) -> Dict[str, Any]:
+        """
+        Sanitize callable params dict, e.g. ``{'a': <function_**** at 0x****>} -> {'a': 'function_****'}``.
+
+        Args:
+            params: Dictionary containing the hyperparameters
+
+        Returns:
+            dictionary with all callables sanitized
+        """
+        def _sanitize_callable(val):
+            # Give them one chance to return a value. Don't go rabbit hole of recursive call
+            if isinstance(val, Callable):
+                try:
+                    _val = val()
+                    if isinstance(_val, Callable):
+                        return val.__name__
+                    return _val
+                except Exception:
+                    return val.__name__
+            return val
+
+        return {key: _sanitize_callable(val) for key, val in params.items()}
+
     @staticmethod
     def _flatten_dict(params: Dict[str, Any], delimiter: str = '/') -> Dict[str, Any]:
         """
diff --git a/pytorch_lightning/loggers/wandb.py b/pytorch_lightning/loggers/wandb.py
index ca2b04d86aea8..e6ce264d597bf 100644
--- a/pytorch_lightning/loggers/wandb.py
+++ b/pytorch_lightning/loggers/wandb.py
@@ -135,6 +135,7 @@ def watch(self, model: nn.Module, log: str = 'gradients', log_freq: int = 100):
     def log_hyperparams(self, params: Union[Dict[str, Any], Namespace]) -> None:
         params = self._convert_params(params)
         params = self._flatten_dict(params)
+        params = self._sanitize_callable_params(params)
         self.experiment.config.update(params, allow_val_change=True)
 
     @rank_zero_only
diff --git a/tests/loggers/test_wandb.py b/tests/loggers/test_wandb.py
index e87d1dff126d9..6682cfdc8830a 100644
--- a/tests/loggers/test_wandb.py
+++ b/tests/loggers/test_wandb.py
@@ -14,6 +14,8 @@
 import os
 import pickle
 from unittest import mock
+from argparse import ArgumentParser
+import types
 
 from pytorch_lightning import Trainer
 from pytorch_lightning.loggers import WandbLogger
@@ -109,3 +111,30 @@ def test_wandb_logger_dirs_creation(wandb, tmpdir):
 
     assert trainer.checkpoint_callback.dirpath == str(tmpdir / 'project' / version / 'checkpoints')
     assert set(os.listdir(trainer.checkpoint_callback.dirpath)) == {'epoch=0.ckpt'}
+
+
+def test_wandb_sanitize_callable_params(tmpdir):
+    """
+    Callback function are not serializiable. Therefore, we get them a chance to return
+    something and if the returned type is not accepted, return None.
+    """
+    opt = "--max_epochs 1".split(" ")
+    parser = ArgumentParser()
+    parser = Trainer.add_argparse_args(parent_parser=parser)
+    params = parser.parse_args(opt)
+
+    def return_something():
+        return "something"
+    params.something = return_something
+
+    def wrapper_something():
+        return return_something
+    params.wrapper_something = wrapper_something
+
+    assert isinstance(params.gpus, types.FunctionType)
+    params = WandbLogger._convert_params(params)
+    params = WandbLogger._flatten_dict(params)
+    params = WandbLogger._sanitize_callable_params(params)
+    assert params["gpus"] == '_gpus_arg_default'
+    assert params["something"] == "something"
+    assert params["wrapper_something"] == "wrapper_something"