Lewis accepted a football scholarship from the University of Michigan. As a freshman he appeared in 13 games, registering 17 tackles and two passes defensed. As a sophomore, he appeared in 12 games, collecting 39 tackles, 28 solo tackles, 1.5 tackles for loss, two interceptions and six passes defensed. He was named a starter in the third game of the season. As a junior, he started 13 games, posting 52 tackles, two interceptions and 20 passes defensed. He also averaged 25.2 yards on kickoff returns. As a senior, he missed the first 3 games with injuries to his back, hamstring and quad. Through the first 10 games of the 2015 season, Lewis had 20 pass breakups, which set a new school record. He ranked second among all players in the NCAA Division I FBS with 21 passes defended. Lewis set a single-season school record with 21 pass breakups in 2015, surpassing the previous record of 18 held by Marlin Jackson and Leon Hall. Following the 2015 season, Lewis was named to the All-Big Ten defensive first-team, by both the media and coaches. He was also named a First-Team All-American by USA Today, and Sports Illustrated, becoming the first Wolverine to earn the honor since Taylor Lewan in 2013, and the first Wolverine defensive back to earn the honor since Leon Hall in 2006. During the 2016 season, Lewis was targeted 31 times, allowing 74 yards, with 14 total yards after catch and 0.36 yards per snap in coverage. Lewis has contributed 23 tackles, 3.5 tackles-for-loss, two interceptions and 12 pass breakups this season. Following the 2016 season, Lewis was named the Tatum–Woodson Defensive Back of the Year, and was once again named to the All-Big Ten defensive first-team, by both the media and coaches. He was also named a first-team All-American by the Walter Camp Football Foundation, Associated Press, Sporting News, and Sports Illustrated.
Professional career
On January 10, 2017, it was reported that Lewis and teammates Chris Wormley and Ben Gedeon had all accepted their invitations to attend the 2017 Senior Bowl. On January 28, 2017, he recorded four combined tackles and displayed impressive coverage under Chicago Bears' head coach John Fox as a part of the North team who lost 16-15 to the South. As a top ten cornerback prospect, Lewis was invited to the NFL combine. He attended and performed the majority of drills, but opted to skip the short shuttle and three-cone drill. On March 18, he opted to participate at Michigan's Pro Day. Lewis chose to run his 40-yard dash, 20-yard dash, 10-yard dash, short shuttle, and three-cone drill for representatives and scouts from all 32 NFL teams. On March 25, Lewis' girlfriend accused him of dragging her across the floor and placing his hands around her neck, although Lewis rebuffed the account claiming he didn't touch her. He pleaded not guilty and this was expected to affect his draft stock. Lewis' draft projections varied from as high as the second or third round to as low as the sixth or seventh round, mainly due to his misdemeanor domestic violence charges. He was ranked the sixth cornerback in the draft by NFL analyst Mel Kiper Jr. and the tenth best cornerback prospect in the draft by NFLDraftScout.com.
2017
Lewis was selected by the Dallas Cowboys in the third round of the 2017 NFL Draft. He was the 14th cornerback selected in 2017. On June 28, the Dallas Cowboys signed Lewis to a four-year, $3.24 million contract that includes a signing bonus of $753,428. He was expected to compete with Orlando Scandrick, Chidobe Awuzie, Anthony Brown, and Nolan Carroll for a job as the starting cornerback, but suffered a hamstring injury during his first training camp practice and missed all of the preseason. On September 17, Lewis made his professional regular season debut against the Denver Broncos after being a healthy scratch for their season-opener. He went into the game after Carroll suffered a concussion and he recorded six solo tackles and intercepted the first pass of his career off of Broncos' quarterback Trevor Siemian in a 42–17 loss. The next week, he earned his first career start in place of Carroll and recorded six solo tackles and deflected a pass in a 28–17 win at the Arizona Cardinals. He suffers a hamstring injury during the game and was questionable going into the following week. During a Week 5 matchup against the Green Bay Packers, he made his second career start and collected seven combined tackles and a season-high three pass deflections in the Cowboys' 35-31 loss. Lewis gave up an 11-yard game-winning touchdown with 11 seconds left in the game to Davante Adams on a back shoulder fade thrown by Aaron Rodgers. Lewis was criticized by FS1 analyst Skip Bayless who attributed the touchdown to the height difference between Adams and Lewis. On October 8, the Cowboys released Carroll, making Lewis the starting right cornerback due to his performances.
2018
Lewis finished the 2018 season with 12 combined tackles, one interception, one pass defensed, and two fumble recoveries in 15 games.
On March 15, 2017, Lewis' girlfriend claimed he had dragged her across the floor and put his hands around her neck to police. His girlfriend of three years had called police after she said an incident had taken place at their apartment. Two officers arrived and she told them the altercation began after an argument about him leaving the lights on and about their bills. She then claimed he threw a pillow at her and went into her closet. When she went to check to see if he was damaging her property, she somehow ended up on the ground and accused Lewis of dragging her across the floor. He supposedly then held her down by her neck for about three seconds. He was not arrested at the time. Lewis denied the claims and pleaded not guilty to a charge of misdemeanor charge of domestic violence the following day. On July 25, 2017, Lewis was found not guilty of all charges. During his tenure with the Wolverines became close friends with Tyler and Tucker Vasher. Tyler and Tucker both are diagnosed with Brittle Bone disease.
