Five players from each league were selected for the Final Vote ballot, which closed at 4 p.m. Friday.
Moustakas is hitting .301 with seven home runs and 31 RBIs on the season. He joins starter Josh Donaldson and reserve Manny Machado as third basemen on the American Roster roster. The Royals now have seven players on the AL roster.
The losing AL candidates were Xander Bogaerts, Yoenis Cespedes and Brian Dozier. Yankees outfielder Brett Gardner had been on the Final Vote ballot, but was removed on Thursday after he was named an All-Star to replace the injured Alex Gordon.
The All-Star Game will be held Tuesday at Great American Ballpark in Cincinnati.
- Molly Geary