2019, following the AAF's suspension of operations, Gilbert signed with the Cleveland Browns of the NFL. He made his debut with the Browns in Week 5, relieving Baker Mayfield in the fourth quarter of a 3–31 loss to the San Francisco 49ers. Gilbert was placed on the reserve/COVID-19 list by the Browns on August 3, 2020, but was activated two days later. On September 5, 2020, Gilbert was waived by the Browns, but re-signed to their practice squad the next day. Dallas Cowboys On October 12, 2020, Gilbert was signed by Dallas Cowboys off the Browns practice squad as a backup to Andy Dalton after Dak Prescott suffered a season-ending ankle injury. The move relocated him back to Texas. On November 7, 2020, Gilbert was named the starting quarterback for the Cowboys’ week 9 game against the undefeated Pittsburgh Steelers, due to Dalton being on the reserve/COVID-19 list and Ben DiNucci’s struggles the previous week against Philadelphia. In his first NFL start, he threw for 243 yards, one touchdown, and one interception, nearly pulling off an upset as the Cowboys ultimately lost 24–19. He returned to a backup role the rest of the season behind Dalton. Gilbert was the starter for Dallas in the Hall of Fame game on August 5, 2021. He was released from the Cowboys during final roster cuts on August 31, 2021. New England Patriots (second stint) On September 2, 2021, Gilbert was signed to the Patriots' practice squad. Washington Football Team On December 17, 2021, the Washington Football Team signed Gilbert off the Patriots' practice squad after both Taylor Heinicke and Kyle Allen were placed on the team's COVID-19 reserve list that same week. With Heinicke and Allen out, Gilbert started against the Philadelphia Eagles on December 21, 2021, just four days after signing with the team. He went 20 of 31 with 194 yards as Washington lost 27–17. Las Vegas Raiders On March 19, 2022, Gilbert signed a contract with the Las Vegas Raiders. On May 12, 2022, the Raiders released Gilbert after trading for Patriots backup quarterback Jarrett Stidham. New England Patriots (third stint) On October 4, Gilbert signed to the Patriots practice squad. On October 15, Gilbert was elevated to the active roster to be the backup quarterback to rookie Bailey Zappe as both Mac Jones and Brian Hoyer were both injured. The elevation was via a standard elevation which caused him