Sims signed with the Washington Redskins as an undrafted free agent on April 30, 2019.[5] He had his first career reception, a three-yard gain from Case Keenum, in a Week 2 loss to the Dallas Cowboys, along with three carries for sixteen yards.[6] He had his first career touchdown, a 65-yard rushing touchdown, against the New England Patriots on October 6, 2019.[7] In Week 12, he had his first kickoff return touchdown, for 91 yards, in a 19–16 win over the Detroit Lions, earning NFC Special Teams Player of the Week.[8][9] In Week 16 against the New York Giants, Sims caught six passes for 64 yards and two touchdowns during the 41–35 overtime loss.[10] Overall, Sims finished the 2019 season with 34 receptions for 310 receiving yards and four touchdowns.[11]
He played the first three games of the 2020 season before being placed on injured reserve for a knee injury on October 9, 2020.[12] He was activated off it on November 7.[13] Sims played twelve games in the regular 2020 season and recorded 27 receptions for 265 yards and one touchdown. In his first playoff appearance, Sims caught three passes for 33 yards and recorded the only Washington receiving touchdown in the Wild Card Playoff game against the Tampa Bay Buccaneers.[14] He was released on August 23, 2021.[15]
Buffalo Bills
Sims signed with the Buffalo Bills on August 25, 2021,[16] but was released on August 31 as part of the Bills' final cuts.[17]
Pittsburgh Steelers
On September 1, 2021, Sims signed with the practice squad of the Pittsburgh Steelers.[18] He signed a reserve/future contract with the Steelers on January 19, 2022.[19]
During the 2022 season, Sims played in 12 games and recorded 14 receptions for 104 yards and 13 rushing attempts for 70 yards.[20]
Houston Texans
On March 24, 2023, Sims signed with the Houston Texans.[21] He was released on August 29, 2023 and re-signed to the practice squad.[22][23] He was promoted to the active roster on January 16, 2024.[24] In the Divisional Round against the Ravens in the playoffs, Sims returned a punt 67 yards for a touchdown in the 34–10 loss.[25]
Sims re-signed with the Texans on March 21, 2024.[26]