He played in Major League Baseball (MLB) for the St. Louis Cardinals, Toronto Blue Jays, and Minnesota Twins.

[6] Walters made his major league debut on April 17, 2009, as the starting pitcher against the Chicago Cubs.

[9] He picked up his first MLB win on May 27, 2010 when he pitched five scoreless innings against the San Diego Padres.

[10] On July 25, 2011, Walters gave up a grand slam to Houston Astros outfielder Carlos Lee.

[5] On July 27, 2011, Walters was traded to the Toronto Blue Jays along with Colby Rasmus, Brian Tallet and Trever Miller for Edwin Jackson, Octavio Dotel, Marc Rzepczynski and Corey Patterson.

[5] He began the season with the AAA Rochester Red Wings, where he was the opening day starter.

[16] However, on November 1, Walters signed a new minor league deal with the Twins that included an invitation to spring training.

[17] The low light of his 2013 season was on June 22, when he didn't even make it out of the first inning while pitching against the Cleveland Indians.

[6] Walters signed a minor league deal with the Kansas City Royals on November 19, 2013,[5] and started the 2014 season with the Triple-A Omaha Storm Chasers.

[20] Walters split the season between the Double-A New Hampshire Fisher Cats and the Triple-A Buffalo Bisons.

[24] He started four games for the Triple-A Oklahoma City Dodgers and one for the Double-A Tulsa Drillers.