Don Sweeney was drafted out of high school by the Boston Bruins in 1984 but went on to attend Harvard University for four years, while becoming an NCAA East All-American team member in 1988 as well as an ECAC First Team All-Star team member.
He made his NHL debut in the 1988-89 season but split the year with the team's AHL affiliate in Maine. Sweeney saw his first action in the Stanley Cup playoffs in 1990 when the Bruins went all the way to the finals, but the team fell to the mighty Edmonton Oilers. The next season saw the Bruins fight their way to the Conference Finals only to run into the Penguins, who dispatched the Bruins on their way to the championship.
A member of Canada's Gold Medal winning team at the 1997 World Championships, Sweeney entered his 15th season with the Bruins organization in 2002-03 and surpassed 1,000 games played.
Although small in stature for a defenceman, over the years Sweeney has not shied away from the physical aspect of the game while chipping in offensively. The St. Stephen, New Brunswick native entered the 2002-03 season tenth on the Bruins all-time point list.
After 15 seasons in Beantown, Sweeney signed as a free agent with the Dallas Stars where he would conclude his NHL playing career. In the summer of 2006, Sweeny would return to Beantown as he was named as the Director of Player Development with the Boston Bruins.