He has played in Major League Baseball (MLB) for the San Francisco Giants, Milwaukee Brewers, Baltimore Orioles, Kansas City Royals and Pittsburgh Pirates.

[9] Susac began the 2014 season with the Fresno Grizzlies of the Class AAA Pacific Coast League (PCL), where he batted .268 in 63 games through July 26.

[10][11][12] Susac flew to San Francisco the next morning and played his first MLB game that evening vs. the Los Angeles Dodgers, grounding out to third base in a single at-bat against Clayton Kershaw who shut out the Giants that day.

[10] Susac got his first major league hit, a single, on July 30, 2014,[13][14] and his first major-league home run (a two-run homer) at Wrigley Field against Chicago Cubs pitcher Edwin Jackson on August 20, 2014.

[19] However, he was set back in Spring Training with a tooth infection and wrist injury and subsequently started the season with the Sacramento River Cats of the PCL.

[21] On June 27, Susac hit a bases-loaded double that drove in three runs and helped the Giants come from behind to defeat the Colorado Rockies 7–5.

[22] In late June, Susac was named the Giants' regular catcher as the team dealt with outfield injuries that pushed Buster Posey to first base and Brandon Belt to left field.

[24] Susac was activated on August 17,[25] but was shut down for the season on September 5 due to lingering effects from the wrist sprain suffered in Spring Training.

During spring training, Susac was set back by his sore right wrist and was optioned to Triple-A Sacramento to start the season.

Susac was designated for assignment on January 11, 2019, after the Orioles claimed Hanser Alberto off waivers from the New York Yankees.