In May 2012, Gibson was named to the US Select Team, joining the likes of Jeremy Lin, DeMarcus Cousins, and Kyrie Irving in practicing with the US Olympic Team in preparation for the 2012 Summer Olympics in London. On October 31, 2012, Gibson signed a multi-year rookie scale contract extension with the Bulls. Playing mostly a bench role in 2013–14, Gibson averaged 13 points and 6.8 rebounds on the season and was among the league leaders in blocked shots per game. He finished second in the NBA's Sixth Man of the Year Award, losing to Jamal Crawford. On June 16, 2015, Gibson underwent arthroscopic surgery on his left ankle and was ruled out for four months. During the 2015–16 season, he appeared in 73 games and averaged 8.6 points and 6.9 rebounds.