diff --git a/CHANGELOG.md b/CHANGELOG.md
index c71f55f8a4db4..aaea00a18b856 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -149,6 +149,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 
 ### Deprecated
 
+- Deprecated `LightningModule.write_predictions` and `LigtningModule.write_predictions_dict` ([#7066](https://github.com/PyTorchLightning/pytorch-lightning/pull/7066))
+
+
 - Deprecated `TrainerLoggingMixin` in favor of a separate utilities module for metric handling ([#7180](https://github.com/PyTorchLightning/pytorch-lightning/pull/7180))
 
 
diff --git a/pytorch_lightning/core/lightning.py b/pytorch_lightning/core/lightning.py
index 445ed76d7d27d..c824502e25ec4 100644
--- a/pytorch_lightning/core/lightning.py
+++ b/pytorch_lightning/core/lightning.py
@@ -406,7 +406,14 @@ def write_prediction(
             when running in distributed mode, calling ``write_prediction`` will create a file for
             each device with respective names: ``filename_rank_0.pt``, ``filename_rank_1.pt``, ...
 
+        .. deprecated::v1.3
+            Will be removed in v1.5.0.
         """
+        rank_zero_deprecation(
+            'LightningModule method `write_prediction` was deprecated in v1.3'
+            ' and will be removed in v1.5.'
+        )
+
         self.trainer.evaluation_loop.predictions._add_prediction(name, value, filename)
 
     def write_prediction_dict(self, predictions_dict: Dict[str, Any], filename: str = 'predictions.pt'):
@@ -426,7 +433,14 @@ def write_prediction_dict(self, predictions_dict: Dict[str, Any], filename: str
             when running in distributed mode, calling ``write_prediction_dict`` will create a file for
             each device with respective names: ``filename_rank_0.pt``, ``filename_rank_1.pt``, ...
 
+        .. deprecated::v1.3
+            Will be removed in v1.5.0.
         """
+        rank_zero_deprecation(
+            'LightningModule method `write_prediction_dict` was deprecated in v1.3 and'
+            ' will be removed in v1.5.'
+        )
+
         for k, v in predictions_dict.items():
             self.write_prediction(k, v, filename)
 
diff --git a/tests/deprecated_api/test_remove_1-5.py b/tests/deprecated_api/test_remove_1-5.py
index 0a838da2faf27..b8f398b9e1c0f 100644
--- a/tests/deprecated_api/test_remove_1-5.py
+++ b/tests/deprecated_api/test_remove_1-5.py
@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 """Test deprecated functionality which will be removed in v1.5.0"""
+import os
 from unittest import mock
 
 import pytest
@@ -244,6 +245,42 @@ def bar(self):
                 pass
 
 
+def test_v1_5_0_lightning_module_write_prediction(tmpdir):
+
+    class DeprecatedWritePredictionsModel(BoringModel):
+
+        def __init__(self):
+            super().__init__()
+            self._predictions_file = os.path.join(tmpdir, "predictions.pt")
+
+        def test_step(self, batch, batch_idx):
+            super().test_step(batch, batch_idx)
+            self.write_prediction("a", torch.Tensor(0), self._predictions_file)
+
+        def test_epoch_end(self, outputs):
+            self.write_prediction_dict({"a": "b"}, self._predictions_file)
+
+    with pytest.deprecated_call(match="`write_prediction` was deprecated in v1.3 and will be removed in v1.5"):
+        model = DeprecatedWritePredictionsModel()
+        trainer = Trainer(
+            default_root_dir=tmpdir,
+            max_epochs=1,
+            checkpoint_callback=False,
+            logger=False,
+        )
+        trainer.test(model)
+
+    with pytest.deprecated_call(match="`write_prediction_dict` was deprecated in v1.3 and will be removed in v1.5"):
+        model = DeprecatedWritePredictionsModel()
+        trainer = Trainer(
+            default_root_dir=tmpdir,
+            max_epochs=1,
+            checkpoint_callback=False,
+            logger=False,
+        )
+        trainer.test(model)
+
+
 def test_v1_5_0_trainer_logging_mixin(tmpdir):
     trainer = Trainer(default_root_dir=tmpdir, max_epochs=1, checkpoint_callback=False, logger=False)
     with pytest.deprecated_call(match="is deprecated in v1.3 and will be removed in v1.5"):