Anderson was acquired from Colorado in 2011 and is now under contract through the 2017-18 season. The 33-year-old goalie will make $4.75 million in 2015-16 and 2016-17 and $3.1 million in 2017-18.
Anderson had an NHL-best .941 save percentage in the lockout-shortened 2013 season to help Ottawa make the playoffs amid injuries. His percentage dropped to .911 last year.
The Senators recently re-signed restricted free-agent goaltender Robin Lehner to a $6.7 million, three-year contract.