New York Jets
Darnold was selected by the New York Jets in the first round, with the third overall selection, of the 2018 NFL draft. On July 30, 2018, he signed a four-year deal worth $30.25 million fully guaranteed featuring a $20 million signing bonus with the Jets.
Darnold made his professional debut in the first preseason game against the Atlanta Falcons on August 10, where he finished with 96 passing yards and a touchdown as the Jets won 17–0. On August 29, the Jets named Darnold the starter for Week 1 of the season.
Darnold played his first regular season game on September 10, 2018, during Monday Night Football against the Detroit Lions. At 21 years, 97 days old, Darnold became the youngest opening-day starting quarterback since the 1970 AFL–NFL merger. His first pass resulted in an interception returned for a touchdown by Quandre Diggs. However, he responded well and finished with 198 passing yards and two touchdowns as the Jets won 48–17. During the Jets' home opener against the Miami Dolphins in Week 2, Darnold finished with 334 passing yards, a touchdown, and two interceptions as the Jets lost 20–12. During a Thursday Night Football game against the Cleveland Browns in Week 3, Darnold finished with 169 passing yards and two interceptions as the Jets lost 21–17. During Week 4 against the Jacksonville Jaguars, Darnold finished with 167 passing yards and a touchdown as the Jets lost 31–12. During Week 5 against the Denver Broncos, Darnold finished with 198 passing yards, three touchdowns, and an interception, while the Jets combined for 323 rushing yards and won 34–16. During Week 6 against the Indianapolis Colts, Darnold finished with 280 passing yards, two touchdowns, and an interception as the Jets won 42–34. During Week 7 against the Minnesota Vikings, Darnold committed 4 turnovers, including 3 interceptions and a lost fumble. He finished with 206 passing yards and a touchdown as the Jets lost 37–17. During Week 8 against the Chicago Bears, Darnold finished with 153 passing yards and a touchdown as the Jets lost 24–10.
During a rematch against the Dolphins in Week 9, Darnold threw four interceptions, finishing the game with 229 passing yards during a 13–6 loss. Darnold suffered through a foot injury, which sidelined him and caused Josh McCown to start for the Jets. After missing three games due to a foot injury, Darnold returned to action in a Week 14 matchup against the Buffalo Bills and fellow rookie quarterback Josh Allen. Darnold temporarily left the game due to an injury on the same foot, but eventually returned, finishing with 170 passing yards, a touchdown, and an interception as the Jets ended their six-game losing streak and won 27–23. He led the team on its game-winning drive, completing a 37-yard pass to Robby Anderson to help set up a touchdown run by Elijah McGuire. During Saturday Night Football against the Houston Texans in Week 15, Darnold finished with 253 passing yards and two touchdowns as the Jets lost 29–22. During Week 16 against the Green Bay Packers, Darnold finished with 341 passing yards and three touchdowns. Marred by 16 penalties, the Jets squandered a 15-point lead and lost 44–38 in overtime. During Week 17 against the New England Patriots, Darnold finished with 167 passing yards as the Jets lost 38–3 in the regular-season finale. Darnold finished the season with 2,865 passing yards, 17 passing touchdowns, and 15 interceptions.
During the Jets' home opener against the Bills in Week 1, Darnold finished with 179 passing yards and a touchdown. Despite the Jets having a 16–0 lead midway through the third quarter and four takeaways, the team lost 17–16. On September 12, it was reported that Darnold was diagnosed with mononucleosis, and he subsequently missed three games. He returned in Week 6 against the Dallas Cowboys where he finished with 338 passing yards, two touchdowns, and an interception as the Jets won 24–22. In the game, Darnold threw a 92-yard touchdown pass to Robby Anderson. He was named the American Football Conference Offensive Player of the Week for his performance. During Monday Night Football against the Patriots in Week 7, the Jets only had 154 total yards of offense with Darnold throwing four interceptions and losing a fumble as the Jets were shut out 33–0. A sound bite captured by NFL Films and ESPN showed Darnold, who was mic'd up, commenting that he was "seeing ghosts" while struggling during the game, which led to mockery by opposing NFL fanbases.
During Week 8 against the Jaguars, Darnold finished with 218 passing yards, two touchdowns, and three interceptions as the Jets lost 29–15. During Week 9 against the Dolphins, Darnold finished with 260 passing yards, a touchdown, and an interception as the Jets lost 26–18. During Week 10 against the New York Giants, Darnold finished with 230 passing yards, 25 rushing yards, and two total touchdowns as the Jets won 34–27. During Week 11 against the Washington Redskins, Darnold finished with 293 passing yards, four touchdowns, and an interception as the Jets won 34–17. During Week 12 against the Oakland Raiders, Darnold finished with 315 passing yards and two touchdowns as the Jets won 34–3. In Week 13, Darnold finished with 239 passing yards, but penalties by the offensive line proved to be costly as the Jets lost 22–6 to the Cincinnati Bengals. During a Dolphins' rematch in Week 14, Darnold finished with 270 passing yards, two touchdowns, and an interception as the Jets won 22–21.
Darnold ended his second professional season with 3,024 passing yards, 19 touchdowns, and 13 interceptions to go along with 33 carries for 62 yards and two touchdowns in 13 games, finishing with a 7–6 record in those starts.
During the season opener against the Bills in Week 1, Darnold finished with 215 passing yards, a touchdown, and an interception as the Jets lost 27–17. During the Jets' home opener against the San Francisco 49ers in Week 2, Darnold finished with 179 passing yards and a touchdown as the Jets lost 31–13. During Week 3 against the Colts, Darnold finished with 168 passing yards, a touchdown, and three interceptions, two of which were returned for a touchdown. He was sacked in the endzone for a safety as the Jets lost 36–7. During Thursday Night Football against the Broncos in Week 4, Darnold finished with 230 passing yards, 86 rushing yards, and highlighted a big play with a 46-yard rushing touchdown. He briefly left the game with a shoulder injury after a sack but was allowed back in the game. Still, the Jets lost 37–28. After missing two games due to shoulder soreness, Darnold returned in Week 7 against the Bills, finishing with 120 passing yards and two interceptions as the Jets lost 18–10. In Week 8 against the Kansas City Chiefs, Darnold reaggravated his shoulder injury and missed the Jets' next two games. He made his return in Week 12 against the Dolphins. During the game, Darnold continued to struggle, throwing for 197 yards and two interceptions in the 20–3 loss. In Week 13 against the Las Vegas Raiders, Darnold threw for 186 yards, two touchdowns, and one interception and also recorded a rushing touchdown during the 31–28 loss. This was Darnold's first game of the season in which he threw more touchdown passes than interceptions.
Darnold finished the 2020 season with 2,208 passing yards, nine touchdowns, and 11 interceptions to go along with 37 carries for 217 yards and two touchdowns in 12 games and starts as the Jets finished 2–14.
