On February 24, 2011, Green was traded, along with Nenad Krstić and a 2012 first-round pick, to the Boston Celtics in exchange for Kendrick Perkins and Nate Robinson. Green recorded a double-double in his first start as a Celtic against the Washington Wizards on April 11, 2011, recording 20 points, a career high-tying 15 rebounds, four assists and two steals. Green improved his field goal percentage after the trade to the Celtics, shooting 48.5 percent from the floor in 26 games after shooting 43.7 percent with the Thunder.