diff --git a/.github/workflows/_legacy-checkpoints.yml b/.github/workflows/_legacy-checkpoints.yml
index 8cceb5870af8d..6c37281fc04ec 100644
--- a/.github/workflows/_legacy-checkpoints.yml
+++ b/.github/workflows/_legacy-checkpoints.yml
@@ -57,28 +57,32 @@ jobs:
     steps:
       - uses: actions/checkout@v5
 
-      - uses: actions/setup-python@v5
+      - name: Install uv and set Python version
+        uses: astral-sh/setup-uv@v6
         with:
-          # Python version here needs to be supported by all PL versions listed in back-compatible-versions.txt.
           python-version: "3.9"
+          # TODO: Avoid activating environment like this
+          # see: https://github.com/astral-sh/setup-uv/tree/v6/?tab=readme-ov-file#activate-environment
+          activate-environment: true
+          enable-cache: true
 
       - name: Install PL from source
         env:
           PACKAGE_NAME: pytorch
           FREEZE_REQUIREMENTS: 1
         timeout-minutes: 20
-        run: pip install . --extra-index-url="${TORCH_URL}"
+        run: uv pip install . --extra-index-url="${TORCH_URL}"
         if: inputs.pl_version == ''
 
       - name: Install PL version
         timeout-minutes: 20
-        run: pip install "pytorch-lightning==${{ inputs.pl_version }}" --extra-index-url="${TORCH_URL}"
+        run: uv pip install "pytorch-lightning==${{ inputs.pl_version }}" --extra-index-url="${TORCH_URL}"
         if: inputs.pl_version != ''
 
       - name: Adjust tests -> PL
         if: ${{ matrix.pkg-name != 'lightning' }}
         run: |
-          pip install -q -r .actions/requirements.txt
+          uv pip install -q -r .actions/requirements.txt
           python .actions/assistant.py copy_replace_imports --source_dir="./tests" \
             --source_import="lightning.fabric,lightning.pytorch" \
             --target_import="lightning_fabric,pytorch_lightning"
@@ -115,7 +119,7 @@ jobs:
         # export to env bool if secrets.AWS_REGION is not empty
         run: echo "WITH_SECRETS=$([ -n '${{ secrets.AWS_REGION }}' ] && echo 1 || echo 0)" >> $GITHUB_ENV
 
-      - run: pip install -r requirements/ci.txt
+      - run: uv pip install -r requirements/ci.txt
       - name: Upload checkpoints to S3
         if: ${{ env.WITH_SECRETS == '1' }}
         working-directory: ${{ env.LEGACY_FOLDER }}
diff --git a/.github/workflows/ci-tests-pytorch.yml b/.github/workflows/ci-tests-pytorch.yml
index f9cfc9a843b6c..86f0a58089481 100644
--- a/.github/workflows/ci-tests-pytorch.yml
+++ b/.github/workflows/ci-tests-pytorch.yml
@@ -69,52 +69,49 @@ jobs:
       TORCH_URL_STABLE: "https://download.pytorch.org/whl/cpu/"
       TORCH_URL_TEST: "https://download.pytorch.org/whl/test/cpu/"
       FREEZE_REQUIREMENTS: ${{ ! (github.ref == 'refs/heads/master' || startsWith(github.ref, 'refs/heads/release/')) }}
-      PYPI_CACHE_DIR: "_pip-wheels"
       # TODO: Remove this - Enable running MPS tests on this platform
       DISABLE_MPS: ${{ matrix.os == 'macOS-14' && '1' || '0' }}
     steps:
       - uses: actions/checkout@v5
 
-      - name: Set up Python ${{ matrix.config.python-version }}
-        uses: actions/setup-python@v5
+      - name: Install uv and set Python version
+        uses: astral-sh/setup-uv@v6
         with:
           python-version: ${{ matrix.config.python-version || '3.9' }}
+          # TODO: Avoid activating environment like this
+          # see: https://github.com/astral-sh/setup-uv/tree/v6/?tab=readme-ov-file#activate-environment
+          activate-environment: true
+          enable-cache: true
 
-      - name: basic setup
-        run: pip install -q -r .actions/requirements.txt
+      - name: Basic setup
+        run: uv pip install -q -r .actions/requirements.txt
 
       - name: Append Env. vars for Linux
         if: ${{ runner.os == 'Linux' }}
         run: echo "GLOO_SOCKET_IFNAME=eth0" >> $GITHUB_ENV
+      - name: Append Env. vars for MacOS
+        if: ${{ runner.os == 'macOS' }}
+        run: echo "GLOO_SOCKET_IFNAME=lo0" >> $GITHUB_ENV
 
       - name: Set min. dependencies
         if: ${{ matrix.config.requires == 'oldest' }}
         run: |
           cd requirements/pytorch
-          pip install -U "lightning-utilities[cli]"
+          uv pip install -U "lightning-utilities[cli]"
           python -m lightning_utilities.cli requirements set-oldest --req_files "['base.txt', 'extra.txt', 'strategies.txt', 'examples.txt', 'test.txt']"
-          pip install "cython<3.0" wheel
-          pip install "pyyaml==5.4" --no-build-isolation
+          uv pip install "cython<3.0" wheel
+          uv pip install "pyyaml==5.4" --no-build-isolation
 
       - name: Adjust PyTorch versions in requirements files
         if: ${{ matrix.config.requires != 'oldest' }}
         run: |
-          pip install -q -r requirements/ci.txt
+          uv pip install -q -r requirements/ci.txt
           python -m wget https://raw.githubusercontent.com/Lightning-AI/utilities/main/scripts/adjust-torch-versions.py
           for fpath in `ls requirements/**/*.txt`; do \
             python ./adjust-torch-versions.py $fpath ${{ matrix.config.pytorch-version }}; \
           done
           cat requirements/pytorch/base.txt
 
-      - name: pip wheels cache
-        uses: actions/cache/restore@v4
-        with:
-          path: ${{ env.PYPI_CACHE_DIR }}
-          key: pypi_wheels
-      - run: |
-          mkdir -p $PYPI_CACHE_DIR
-          ls -lh $PYPI_CACHE_DIR
-
       - name: Env. variables
         run: |
           # Switch PyTorch URL between stable and test/future
@@ -129,20 +126,22 @@ jobs:
       - name: Install package & dependencies
         timeout-minutes: 20
         run: |
-          pip install ".[${EXTRA_PREFIX}extra,${EXTRA_PREFIX}test,${EXTRA_PREFIX}strategies]" \
-            -U --upgrade-strategy=eager --prefer-binary \
+          uv pip install ".[${EXTRA_PREFIX}extra,${EXTRA_PREFIX}test,${EXTRA_PREFIX}strategies]" \
+            --upgrade \
             -r requirements/_integrations/accelerators.txt \
-            --extra-index-url="${TORCH_URL}" \
-            --find-links="${PYPI_CACHE_DIR}" \
+            --find-links="${TORCH_URL}" \
             --find-links="https://download.pytorch.org/whl/torch-tensorrt"
-          pip list
+          uv pip list
+
       - name: Drop LAI from extensions
         if: ${{ matrix.config.pkg-name != 'lightning' }}
         # Lightning is dependency of Habana or other accelerators/integrations so in case we test PL we need to remove it
-        run: pip uninstall -y lightning
+        run: uv pip uninstall lightning
+
       - name: Drop PL for LAI
         if: ${{ matrix.config.pkg-name == 'lightning' }}
-        run: pip uninstall -y pytorch-lightning
+        run: uv pip uninstall pytorch-lightning
+
       - name: Dump handy wheels
         if: github.event_name == 'push' && github.ref == 'refs/heads/master'
         continue-on-error: true
@@ -219,6 +218,9 @@ jobs:
           name: CPU-coverage
           fail_ci_if_error: false
 
+      - name: Minimize uv cache
+        run: uv cache prune --ci
+
   pl-cpu-guardian:
     runs-on: ubuntu-latest
     needs: pl-cpu
diff --git a/tests/legacy/generate_checkpoints.sh b/tests/legacy/generate_checkpoints.sh
index 1d083a2a8e052..d3cfa693c2906 100644
--- a/tests/legacy/generate_checkpoints.sh
+++ b/tests/legacy/generate_checkpoints.sh
@@ -7,18 +7,17 @@
 set -e
 
 LEGACY_FOLDER=$(cd $(dirname $0); pwd -P)
-printf "LEGACY_FOLDER: $LEGACY_FOLDER"
+printf "LEGACY_FOLDER: $LEGACY_FOLDER\n"
 TESTS_FOLDER=$(dirname $LEGACY_FOLDER)
-ENV_PATH=$LEGACY_FOLDER/vEnv
-printf "ENV_PATH: $ENV_PATH"
+ENV_PATH=$LEGACY_FOLDER/.venv
+printf "ENV_PATH: $ENV_PATH\n"
 export PYTHONPATH=$TESTS_FOLDER  # for `import tests_pytorch`
-printf "PYTHONPATH: $PYTHONPATH"
+printf "PYTHONPATH: $PYTHONPATH\n"
 rm -rf $ENV_PATH
 
 function create_and_save_checkpoint {
-  python --version
-  python -m pip --version
-  python -m pip list
+  uv --version
+  uv pip list
 
   python $LEGACY_FOLDER/simple_classif_training.py $pl_ver
 
@@ -33,10 +32,10 @@ do
   printf "\n\n processing version: $pl_ver\n"
 
   # Don't install/update anything before activating venv to avoid breaking any existing environment.
-  python -m venv $ENV_PATH
+  uv venv $ENV_PATH
   source $ENV_PATH/bin/activate
 
-  python -m pip install "pytorch_lightning==$pl_ver" \
+  uv pip install "pytorch_lightning==$pl_ver" \
     -r $LEGACY_FOLDER/requirements.txt \
     -r "$(dirname $TESTS_FOLDER)/requirements/pytorch/test.txt" \
     -f https://download.pytorch.org/whl/cpu/torch_stable.html
@@ -52,7 +51,7 @@ done
 if [[ -z "$@" ]]; then
   printf "\n\n processing local version\n"
 
-  python -m pip install \
+  uv pip install \
     -r $LEGACY_FOLDER/requirements.txt \
     -r "$(dirname $TESTS_FOLDER)/requirements/pytorch/test.txt" \
     -f https://download.pytorch.org/whl/cpu/torch_stable.html