As a senior in 2007–08, he was named a McDonald's All-American and earned Parade All-America first team honors after averaging 21.0 points and 14.0 rebounds per game.

After coming off the bench for the first month of the season, Monroe made his first career start on December 10, 2010, against the Minnesota Timberwolves.

On May 4, 2011, Monroe placed sixth in NBA Rookie of the Year voting totals, finishing closely behind Gary Neal of San Antonio.

[8] On June 30, 2014, the Pistons tendered a one-year qualifying offer to make Monroe a restricted free agent.

[9] On September 8, 2014, it was announced Monroe signed the Pistons' qualifying offer, thus making him an unrestricted free agent in 2015.

[12] On April 8, 2015, he returned to action after missing 11 games with a knee injury to record 19 points and 10 rebounds in another loss to the Celtics.

[14][15] He made his debut for the Bucks in their season opener on October 28, 2015, recording 22 points and 14 rebounds in a 122–97 loss to the New York Knicks.

[16] Between February 9 and March 7, 2016, Monroe had a 12-game bench stint as head coach Jason Kidd tinkered with his line-up.

[21] He made his debut for the Suns on November 16, 2017, recording 20 points and 11 rebounds in 26 minutes as a starter in a 142–116 loss to the Houston Rockets.

[32] On July 25, 2019, Monroe signed with Bayern Munich of the German Basketball Bundesliga (BBL) and EuroLeague for the 2019–20 season.

[33] On July 30, 2020, Monroe signed with Russian club Khimki of the VTB United League and the EuroLeague for the 2020–21 season.

[34] He was named league player of the week on November 11, after contributing 28 points and ten rebounds in an 86–78 win against PBC CSKA Moscow.

[42] The same day, he scored six points and grabbed six rebounds in 15 minutes of playing time in his debut, during a 137–108 win over the Portland Trail Blazers.

[48] On September 26, 2024, Monroe retired from professional basketball and was hired by the New Orleans Pelicans as a player development coach.