On February 27, 2008, after resting for most of the 2007–08 season and weighing his options, Brown signed with the Boston Celtics for the remainder of the season, in order to bolster their front court. His decision to come to Boston was strongly aided by a conversation with future teammates Ray Allen and Paul Pierce, who convinced him to sign with the Celtics during the 2008 NBA All-Star Weekend. The San Antonio Spurs and New Orleans Hornets were interested in his services, but he chose the Celtics instead. He made his debut against the Chicago Bulls, his former team, on March 7, 2008.