Coming out of LSU, Mills draft projection varied as NFL draft experts and scouts were split. NFL analyst Mel Kiper, CBS Sports, and other draft analysts projected him to be selected as early as the second or third round, while others projected a sixth or seventh round selection. Although he was thought as a top draft pick during his junior year, his stock fell when he suffered a fractured fibula and tore ligaments in his ankle in August 2015. He received an invitation to the NFL combine and completed all of the required combine drills. His 40-yard dash time was mediocre and tied for 33rd among all defensive back prospects. On March 14, 2016, he participated at LSU’s pro day and opted to have another attempt at the 40, 20, and 10-yard dash. Mills raised his draft stock after lowering his 40-yard dash time (4.48), but wasn’t able to greatly change his combine numbers in the 20 and 10-yard dash. All 32 NFL teams were represented by coaches and scouts to watch Mills, Deion Jones, Vadal Alexander, Lamar Louis, Jerald Hawkins, Quentin Thomas, Reid Ferguson, and five others perform drills at LSU’s pro day. He was ranked the eighth best cornerback prospect by Sports Illustrated and the ninth best cornerback by NFLDraftScout.com.
The Philadelphia Eagles selected Mills in the seventh round (233rd overall) of the 2016 NFL Draft.
On May 4, 2016, the Philadelphia Eagles signed Mills to a four-year, $2.41 million contract that included a signing bonus of $75,856.
He competed with Eric Rowe, Ron Brooks, Denzel Rice, and Aaron Grymes for a backup cornerback job throughout training camp. Head coach Doug Pederson named Mills the fourth cornerback on the Philadelphia Eagles’ depth chart to begin the regular season, behind Nolan Carroll, Leodis McKelvin, and Ron Brooks.
On September 11, 2016, Mills made his professional regular season debut in the Philadelphia Eagles’ season-opener against the Cleveland Browns and he recorded two solo tackles in the 29–10 victory. The following week, Mills collected a season-high six solo tackles and defended a pass during a 29–14 win over the Chicago Bears. On October 16, 2016, he earned his first career start and recorded a season-high seven combined tackles and two pass deflections during a 20–27 loss to the Washington Redskins. Overall, he played in all 16 games with two starts as a rookie, recording 61 combined tackles (51 solo) and seven passes defensed.
Mills deflecting pass vs Redskins week 1, 2017
He competed with Patrick Robinson, Ron Brooks, Aaron Grymes, and Rasul Douglas for one of the vacant starting cornerback jobs left by the departures of Nolan Carroll and Leodis McKelvin. Mills was named the starting cornerback along with Patrick Robinson to begin the regular season.
On September 10, 2017, Mills recorded nine combined tackles, two pass deflections, and made his first career interception off of a pass attempt by Kirk Cousins during a 30–17 win against the Washington Redskins in the Eagles’ season-opener. He made the interception in the end-zone and returned it for 15-yards. In a Week 3 matchup against the New York Giants, Mills recorded a season-high 12 combined tackles and deflected two passes in a 27-24 victory. On October 12, 2017, in Week 7, Mills collected four combined tackles, deflected a pass, and intercepted a pass attempt from Cam Newton in a 28–23 win over the Carolina Panthers on Thursday Night Football.
On October 29, 2017, in Week 8 against the San Francisco 49ers, Mills recorded three combined tackles, a deflected pass, a tackle for a loss, and intercepted a pass attempt that he returned for a touchdown. For this, he was named NFC Defensive Player of the Week.
On January 21, 2018 in the NFC Championship Mills has 3 tackles, one pass deflection and only gave up two passes for 27 yards in the Eagles’ 38–7 rout of the Minnesota Vikings. Mills appeared in his first career Super Bowl and the Eagles’ 3rd appearance in franchise history, which they would later win against the Patriots, 41-33