On March 2, 2015, at the NHL trade deadline, Connolly was traded to the Boston Bruins in exchange for two second-round draft picks in 2015 and 2016. On March 4, he fractured his hand in his second skate with the Bruins. On April 3, Connolly made his debut with the Bruins, recording two assists in Boston's 3–2 win over the Detroit Red Wings.