While hitting his fifth, sixth and seventh homers this season, the second-year first baseman overshadowed a nice effort by winning pitcher Edinson Volquez.
Later, Brandon Phillips and Votto hit solo homers in the fifth and Votto capped the scoring with his third homer in the sixth.
Volquez (5-1) limited Chicago to four hits in seven scoreless innings with six walks and a career-high 10 strikeouts.
The seven homers were two shy of the club's single-game record of nine at Philadelphia on Sept. 4, 1999.
Six players had one hit each for the Cubs, who are 3-7 in their last 10 games.
The losing pitcher was starter Jon Lieber (2-2).