The deal will pay him $1.6 million next season, $1.7 million in 2012-13 and $1.8 million in 2013-14.
"Coming here I didn't really expect anything, just to come in here and play well and help the team," Stuart told the Atlanta Journal-Constitution. "It was nice to get a deal done. I like it here a lot. I've very comfortable here. I like the people a lot and I think the team has a lot of potential."
Before the trade, Stuart, 6-foot-2, 215 pounds, had spent his entire six-year career with Boston.
The Thrashers made a couple of other moves Monday. They acquired forward Radek Dvorak and a fifth-round pick in this year's draft from the Florida Panthers in exchange for forwards Niclas Bergfors and Patrick Rissmiller.
Dvorak, who had seven goals and 21 points for the Panthers, can
be an unrestricted free agent after the season. Bergfors is a
pending restricted free agent.
Bergfors has 29 points, including 11 goals, for Atlanta. He has
74 points in 142 career games with Atlanta and New Jersey.
Rissmiller played in only one game with Atlanta this season.
Modin, 36, had 10 points, including seven goals, in 36 games
this season. He signed with Atlanta as a free agent on Sept. 6,
2010. In his NHL career, he has 232 goals and 230 assists with
Toronto, Tampa Bay, Columbus, Los Angeles and Atlanta.
Pierre LeBrun covers the NHL for ESPN.com.