Zack Cozart also homered for the light-hitting Reds, who collected a season-best 17 hits.
The Rockies gave up five homers after entering the game having allowed a major league-low 15 in the month of May.
Dan Straily (3-2) overcame a slow start and an early 5-1 deficit to pick up the win. He helped himself by drawing a walk and scoring a run in Cincinnati's five-run fourth inning rally that turned things around.
Votto led off the seventh with his eighth homer, a no-doubt shot off Jason Motte over the scoreboard in right that made him the seventh Reds player to have 200 homers among his 1,000-plus career hits.