Sutton, who turns 35 on March 10, has 34 goals and 101 assists in 567 career games with San Jose, Minnesota, Atlanta and the Islanders. The 6-foot-6 defenseman has 984 penalty minutes, including 73 this season while posting four goals and eight assists in 54 games with New York.
"We wanted to get a little more depth on the blue line and I think Andy fits that need," Senators general manager Bryan Murray said. "I wanted somebody I could look up to -- and I have to do that -- and then up front with Matt Cullen it gives us the versatility that I talked about so it doesn't appear there's much more going to happen. But who knows at the end of the day what might stick its head up and maybe be available."
Sutton's 153 blocked shots this season are second overall in the league. Volchenkov leads the Senators with 137.
"Now the goaltenders don't have to be as good," Murray said. "We hope that they block lots of shots, and they will, and they're both very forceful guys in their own end. We felt that we had enough mobility to have a guy like Andy come in with [Anton Volchenkov] still here and it would work."
Sutton did not play for the Senators in Tuesday night's game against the New York Rangers. He was expected to arrive in Ottawa later in the evening.
"It's an unbelievable opportunity," Sutton said in an audio clip provided by the team. "That's the first thing I said to Bryan, I thanked him so much for the opportunity. Being an older player and getting the chance to play on such a great team and have a chance to win the Stanley Cup is a dream come true."
The second-round draft choice obtained by the Islanders originally belonged to San Jose, which dealt the pick to Ottawa as part of the Sept. 12 trade in which the Senators sent Dany Heatley to the Sharks for Milan Michalek and Jonathan Cheechoo.
Murray dealt another second-round pick in 2010 along with defenseman Alexandre Picard to acquire Cullen from Carolina on Feb. 12.
"We're fortunate we had that second second-round pick," Murray said. "I don't know that the amateur [scouting] guys are real happy with me at the moment but we have a fairly decent hockey team that is competitive and I wanted to give them every chance they deserved come playoff time -- if we get there -- and I think we've sent the message to the players now that we care, we want to win, we're going to help them in any way we can and this is the way we can help them."
ESPN.com's Pierre LeBrun and The Associated Press contributed to this report.