He accepted a scholarship to the University of Wisconsin where he was a member of the Wisconsin Badgers football team from 2009 to 2013. He set a school record by playing in 54 games, never missing a game over his four-year career. He started 30 games for the Badgers, recording 152 total tackles and 11.5 tackles for loss, forcing four fumbles, adding two interceptions and breaking up 11 passes.
During the 2015 offseason, the Atlanta Falcons hired Dan Quinn as their head coach, replacing the outgoing Mike Smith. Quinn quickly changed Southward to a cornerback, from his natural safety position, and praised Southward's "speed and length".[5]
Southward was waived by the Falcons on November 6, 2015, after appearing in just three games for the Falcons.[6]
Indianapolis Colts
Southward was signed to the practice squad of the Indianapolis Colts on November 10, 2015.[7] On August 30, 2016, Southward was placed on injured reserve.[8] On September 7, 2016, he was released from their injured reserve with an injury settlement.
Carolina Panthers
On December 28, 2016, Southward was signed to the Carolina Panthers' practice squad.[9] He signed a reserve/future contract with the Panthers on January 12, 2017.[10]
On September 2, 2017, Southward was waived by the Panthers and was signed to the practice squad the next day.[11][12] He was promoted to the active roster on October 6, 2017.[13] He was waived on October 16, 2017, and was re-signed to the practice squad the next day.[14] He signed a reserve/future contract with the Panthers on January 8, 2018.[15]
On September 1, 2018, Southward was waived by the Panthers and was signed to the practice squad the next day.[16][17] He was released on September 11, 2018, but was re-signed on September 24.[18][19] He was released again on October 30, 2018.[20]