conda install -c conda-forge matplotlib

Warning

uv usually installs its own versions of Python from the python-build-standalone project, and only recent versions of those Python builds (August 2025) work properly with the tkagg backend for displaying plots in a window. Please make sure you are using uv 0.8.7 or newer (update with e.g. uv self update) and that your bundled Python installs are up to date (with uv python upgrade --reinstall). Alternatively, you can use one of the other supported GUI frameworks, e.g.

uv add matplotlib pyside6