The award, announced Tuesday at baseball meetings in Nashville, is determined by a vote of beat writers, broadcasters and American League public relations departments. Butler received 80 of the possible 84 first-place votes. Toronto's Edwin Encarnacion was second.
Butler had 29 home runs and 107 runs batted in in 161 games for the Royals in 2012. He was the first Kansas City player to hit at least .300 with 25 home runs and 100 RBI in a season since 2003. His 29 home runs are the most for a Royals player since Jermaine Dye hit 33 in 2000.
He's played his entire six-season career in Kansas City and in 2012 posted career highs for games, at-bats (614), hits (192), home runs and RBI. He led the team in batting, home runs and RBI.
Butler, 26, is the second Kansas City player to win the award, which has been voted on since the designated hitter was instituted in 1973. The Royals' Hal McRae won the honor in 1976, 1980 and 1982.