On December 12, 2011, Bass was traded to the Boston Celtics in exchange for Glen Davis and Von Wafer.
In his first regular season game for the Celtics on December 25, 2011, he recorded 20 points and 11 rebounds in a 104-106 loss to the New York Knicks.
On May 21, 2012, Bass tallied a playoff career-high 27 points to help the Celtics gain a 3-2 series lead over the Philadelphia 76ers.
The Celtics won that series, but were eliminated in the next round by the Miami Heat.
In the 2011–12 season, Bass established his career-high points average to 12.5 and his rebounds to 6.2 that increased the Celtics' offense and defense.

On July 14, 2012, Bass re-signed with the Celtics.

In January 2015, Bass re-gained his starting spot and finished the season averaging 10.6 points and 4.9 rebounds per game.
On December 12, 2011, Bass was traded to the Boston Celtics in exchange for Glen Davis and Von Wafer. In his first regular season game for the Celtics on December 25, 2011, he recorded 20 points and 11 rebounds in a 104-106 loss to the New York Knicks. On May 21, 2012, Bass tallied a playoff career-high 27 points to help the Celtics gain a 3-2 series lead over the Philadelphia 76ers. The Celtics won that series, but were eliminated in the next round by the Miami Heat. In the 2011–12 season, Bass established his career-high points average to 12.5 and his rebounds to 6.2 that increased the Celtics' offense and defense.
On July 14, 2012, Bass re-signed with the Celtics.
In January 2015, Bass re-gained his starting spot and finished the season averaging 10.6 points and 4.9 rebounds per game.
Brandon Bass