Twig and Jinja share a common syntax, so to get syntax highlighting going in TextMate we are going to borrow one of the bundles already made for it.
Open up terminal and run the following:
mkdir -p ~/Library/Application\ Support/TextMate/Bundles
cd ~/Library/Application\ Support/TextMate/Bundles
git clone http://github.com/ozan/textmate-jinja-templates.git "Jinja Templates.tmbundle"
osascript -e 'tell app "TextMate" to reload bundles'
Next, jump into TextMate Bundle Editor (Ctrl+Opt+Cmd+B) and go to the Jinja Templates bundle, open the "HTML (Jinja Templates)" language and change the following line from