In his first year with the Badgers in 2013, Shelton played all 13 games in the season which included 12 starts at cornerback, in which he recorded thirty-six tackles, four interceptions, and seven pass breakups. He became the first true freshmen to start in a season opener since Travis Frederick in 2009. In 2014, he had a season that only included 33 tackles and 6 pass breakups. In 2015, Shelton seemed to have an increasingly mediocre season, statistically. He recorded 27 tackles, one interception, and seven pass breakups. His sole interception came in the fourth quarter of the 2015 Holiday Bowl helping seal a 23-21 victory over The University of Southern California Trojans. In his final season with Wisconsin in 2016, he had a career high season in interceptions and pass breakups with 4 interceptions and 12 pass-breakups. On November 26, 2016, he logged a 2 interception game against Minnesota.
Professional career
After what most analysts called an "above average" career at Wisconsin, he was projected to go undrafted by NFL.com. He was invited to the 2016 NFL Combine, where he performed in every workout besides the splits. He achieved a 4.02 second 20-yard shuttle, which ranked third best in his position. He attended the Wisconsin Badgers Pro day, where he chose to only do the 40 yard dash, broad jump, and three cone drill.
Arizona Cardinals
Shelton was signed by the Arizona Cardinals as an undrafted free agent on May 2, 2017. He was waived on September 2, 2017.
Cincinnati Bengals
On September 4, 2017, Shelton was signed to the Cincinnati Bengals' practice squad. He was released on October 27, 2017. On November 14, 2017, Shelton was signed back to the Bengals practice squad. He signed a reserve/future contract with the Bengals on January 1, 2018. On August 23, 2018, Shelton was waived by the Bengals.
On August 11, 2019, Shelton was signed by the Philadelphia Eagles. He was waived during final roster cuts on August 30, 2019.
Arizona Cardinals (second stint)
On November 13, 2019, Shelton was signed to the Arizona Cardinals practice squad. He signed a reserve/future contract with the Cardinals on December 30, 2019. On June 1, 2020, Shelton was released by the Cardinals.