Tigers general manager Dave Dombrowski referred to Rondón as a "rare talent" after the 2012 season, and indicated that he could become the Tigers closer in 2013. Rondón struggled early in spring training, but began to improve with mechanical changes. The Tigers optioned Rondón to Toledo for the start of the 2013 season. They promoted him to the major leagues on April 23, but did not use him as their closer. He made his Major League debut on April 25, 2013 against the Kansas City Royals. He entered the game in relief in the eighth inning. His first batter faced was Billy Butler, who singled to right field. His pitching line for this first inning was two hits, one run scored.
Bruce returned to Toledo in early May, where he posted 14 saves and a 1.52 ERA, with 40 strikeouts and 13 walks in 29⁄3 innings. The Tigers recalled him to the major league club on June 28, 2013. He earned his first major league save on August 30, 2013 against the Cleveland Indians. He posted a 3.45 ERA in his first major league season, striking out 30 batters in 28⁄3 innings.