Aquino hit a two-run homer in the first inning Thursday night against the Miami Marlins' Robert Dugger. Aquino broke the rookie mark of 13 in a month set by the Los Angeles Dodgers' Cody Bellinger in June 2017.
The major league rookie record is 18 by the Detroit Tigers' Rudy York in August 1937.
Sammy Sosa holds the record for homers in a month by any major leaguer with 20 in June 1998.
Aquino tied the Reds' record for homers in a month held by Frank Robinson (1962) and Greg Vaughn (1999).
Promoted from the minors on Aug. 1, Aquino already was the first major leaguer in the modern era to reach 13 homers in his first 100 career plate appearances.