Anderson was 25-11-4 last season with a 2.28 goals-against average, .916 save percentage and five shutouts in 40 games. He took a two-month leave of absence from December to February to be with his wife, Nicholle, who had throat cancer and is now in remission.
Anderson was 11-8 with a 2.34 GAA and .922 save percentage in 19 Stanley Cup Playoff games, and won the Masterton Trophy for perseverance and dedication to hockey.
Condon, 27, started 27 consecutive games during Anderson's absence. He was 19-14-6 with a 2.48 GAA and .914 save percentage in 40 games. Condon was acquired in a trade with the Pittsburgh Penguins on Nov. 2.
"It's been a great home for me in Ottawa and I'm really looking forward to playing it out here and continuing to contribute to the team and the organization," Anderson said. "I'm just really ecstatic about being able to be part of this group and part of this team.
"We talked about it pretty much all summer, Nicholle and I, just trying to figure out what's best for our family and my career and where we kind of wanted things to go and play out. Everything kind of boiled down to, I still love the game, I still want to be here, I still want to come and compete on a daily basis. I feel like that fire is still very strong.
"You know when it's time [to retire], and I felt very strongly like I've got lots of time left."
Acquired by the Senators in a trade with Colorado Avalanche for goaltender Brian Elliott on Feb. 18, 2011, Anderson is Ottawa's all-time leader among goaltenders in games played (293) and wins (151).
Anderson is tied for fifth in save percentage (.921) in the NHL over the past three seasons.