Harrell, who appeared in 63 games and averaged 18.6 points, 7.1 rebounds, 1.7 assists, and 1.1 blocks in 27.8 minutes per game this season, helped the Clippers clinch the second seed in the Western Conference.
The 26 year-old beat out fellow finalists Dennis Schröder and teammate Lou Williams for the award.
'Sweet Lou' has won the award three separate times, and even told the press that he didn't mind if Harrell won it this year. Both Lou & 'Trezz' averaged each more than 18 points per game off the bench.
“Over the years, we’ve made history, and we’re on the No. 2 team in the West,” Williams said. “I feel like we both deserve it. I really would love to share that award with Trez, and if not share it, I say give it to him outright.”
He is the first big man to be named Sixth Man of the Year since Lamar Odom in 2011.