Jekyll static site generation on a subsite?

Is it possible to have Jekyll on a single subsection of my website hosted on GitHub? i.e. is it possible to have "example.github.io" be a regular site and "example.github.io/blog" be statically generated by Jekyll?

I believe it's possible to do this by creating another GitHub repo called "blog" and having that repo managed by Jekyll. I'm wondering if it can all be done in one main "example.github.io" repo.

Thanks!