Matawalu has made 10 Premiership appearances since joining Bath from Pro 12 club Glasgow ahead of last season.
The 27-year-old, who can also play as a winger, has won 28 international caps.
"He's an exciting player, someone you describe as an 'X-Factor' type player," Chiefs head coach Rob Baxter told the club's website.
"We're not expecting him to be 100% straight away as he has had a relatively lengthy injury, but he's fully fit now, he's ready to play, and we're hoping he will get some good game time during these autumn internationals."
Exeter have signed Fiji international scrum-half Niko Matawalu from Bath until the end of the season, with a view to a longer term deal.