The Baseball Digest awards are voted on by a 17-member panel of writers, broadcasters, former players, managers and executives. Freeman finished ahead of the White Sox José Abreu for Player of the Year, receiving eight of the 17 first-place votes.
Abreu received four first-place votes, while Mookie Betts received three votes. Fernando Tatis Jr. and Marcell Ozuna each received one vote.
Freeman batted .341 with 13 home runs, 53 RBIs and an 1.102 OPS for the National League East champions this season. He led the Major Leagues with 51 runs scored, 23 doubles and 37 extra-base hits.
Freeman also finished second in the NL batting race and was second in the league in RBIs, OPS, on-base percentage (.462) and slugging percentage (.640), as well as third in both hits (73) and walks (45).
For Pitcher of the Year, Bieber received all 17 first-place votes to win the award over the Reds' Trevor Bauer and the Cubs' Yu Darvish.
Bieber won the MLB pitching Triple Crown as the first pitcher to lead the Majors in wins, ERA and strikeouts since Johan Santana for the Twins in 2006. He's the first Indians pitcher to win the American League Triple Crown since Hall of Famer Bob Feller in 1940.
Bieber went 8-1 in his 12 starts for the Tribe this season with a 1.63 ERA and 122 strikeouts, becoming the fastest starting pitcher in the modern era to reach 100 strikeouts in a season.
Williams' devastating changeup made him the most dominant reliever in the Majors all season. The 26-year-old right-hander had a breakout campaign for Milwaukee, finishing with a 0.33 ERA and 53 strikeouts, both tops among relievers. Williams struck out over half the batters he faced in his 22 appearances.
Williams received 12 of the 17 first-place votes for Reliever of the Year, while A's closer Liam Hendriks, the runner-up, received four. Alex Colomé of the White Sox also got one first-place vote.