diff --git a/CHANGES.md b/CHANGES.md
index f5b123e8a70..13b57e76959 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -63,6 +63,7 @@
 - Fix the version check in the vim file to reject Python 3.8 (#4567)
 - Enhance GitHub Action `psf/black` to read Black version from an additional section in
   pyproject.toml: `[project.dependency-groups]` (#4606)
+- Build gallery docker image with python3-slim and reduce image size (#4686)
 
 ### Documentation
 
diff --git a/gallery/Dockerfile b/gallery/Dockerfile
index 7a18b7e9a18..ced85e58e6e 100644
--- a/gallery/Dockerfile
+++ b/gallery/Dockerfile
@@ -1,11 +1,12 @@
-FROM python:3.8.2-slim
+FROM python:3-slim
 
 # note: a single RUN to avoid too many image layers being produced
 RUN apt-get update \
  && apt-get upgrade -y \
- && apt-get install git apt-utils -y \
+ && apt-get install git apt-utils -y --no-install-recommends\
  && git config --global user.email "black@psf.github.com" \
- && git config --global user.name "Gallery/Black"
+ && git config --global user.name "Gallery/Black" \
+ && rm -rf /var/lib/apt/lists/*
 
 COPY gallery.py /
 ENTRYPOINT ["python", "/gallery.py"]