diff --git a/src/lightning/pytorch/tuner/batch_size_scaling.py b/src/lightning/pytorch/tuner/batch_size_scaling.py
index 6618f7e930ca1..772ce7762b4c6 100644
--- a/src/lightning/pytorch/tuner/batch_size_scaling.py
+++ b/src/lightning/pytorch/tuner/batch_size_scaling.py
@@ -63,6 +63,9 @@ def _scale_batch_size(
         rank_zero_warn("Skipping batch size scaler since `fast_dev_run` is enabled.")
         return None
 
+    # Capture whether the module is in training or eval mode
+    is_training = trainer.training
+
     # Save initial model, that is loaded after batch size is found
     ckpt_path = os.path.join(trainer.default_root_dir, f".scale_batch_size_{uuid.uuid4()}.ckpt")
     trainer.save_checkpoint(ckpt_path)
@@ -95,6 +98,12 @@ def _scale_batch_size(
     trainer._checkpoint_connector.restore(ckpt_path)
     trainer.strategy.remove_checkpoint(ckpt_path)
 
+    # Set the module back to it's original mode based on the is_training parameter
+    if is_training:
+        trainer.lightning_module.train()
+    else:
+        trainer.lightning_module.eval()
+
     return new_size