Stars General Manager Joe Nieuwendyk said Dallas would receive a conditional second-round pick in the 2013 NHL Draft and young minor-league forwards Lane MacDermid and Cody Payne in return.
"Jaromir Jagr produced as a consistent scorer for our team all year and we would like to thank him for his contributions to our hockey club," Nieuwendyk said. "With our eye to the future, we have acquired some valuable assets that we believe strengthen our organization."
Jagr, 41, was the Stars' leading scorer this season with 14 goals and 26 points.
The Czech Republic native has racked up 679 goals and 1,000 assists in 1,380 career games.
He is expected to provide some scoring punch for the Bruins, who hold the fourth seed in the Eastern Conference with less than four weeks to go in the regular season.
The Stars are the 12th spot in the West, three points out of a playoff slot.