Votto drove a 3-0 pitch from Boone Logan (1-1) over the wall in center for his fifth homer. Votto's fourth career game-ending shot traveled an estimated 437 feet.
Arenado went 0-for-3, snapping his hitting streak at a club-record 28 games, the longest in the majors this season. But Arenado walked and scored on Justin Morneau's tying double in the ninth, handing Jonathan Broxton (1-0) his first blown save in six opportunities.
Cincinnati's Johnny Cueto went eight innings, giving him five consecutive starts of eight or more innings. He gave up five hits and two runs with one walk and eight strikeouts.