Add this line to your application’s Gemfile:

$ gem 'jekyll-gist'

And then execute:

$ bundle

Or install it yourself as:

$ gem install jekyll-gist

Then add the following to your site’s _config.yml:

plugins:
  - jekyll-gist

If you are using a Jekyll version less than 3.5.0, use the gems key instead of plugins. Use the tag as follows in your Jekyll pages, posts and collections by adding {% gist id %}.