He played college football for the USC Trojans, winning the Archie Griffin award in 2016, and was selected third overall by the New York Jets in the 2018 NFL draft.

He joined the Vikings in 2024, where he experienced a career resurgence after becoming their starter that year, leading them to a playoff appearance and earning Pro Bowl honors.

During a football camp, USC coaches Clay Helton and Steve Sarkisian were impressed by Darnold's performance,[7] and extended to him a scholarship to play for the Trojans.

[8] Sources: USC defensive coordinator Justin Wilcox, who recruited Darnold to the school, wanted him to play linebacker before he declined.

[11] After the loss, Darnold's Trojans did not lose a game for the remainder of the season, including a 26–13 upset win over the #4-ranked Washington Huskies.

[16][17] Entering the 2017 season as a redshirt sophomore, Darnold became an early favorite for the Heisman Trophy, and eventually a first-round pick in the 2018 draft.

[18] He then led an overtime victory over the Texas Longhorns during which he drove the Trojans to a game-tying field goal in the final 39 seconds of regulation.

[20] The win earned USC a spot in the 2017 Cotton Bowl where, despite having 356 passing yards, the Trojans were defeated by the Ohio State Buckeyes, 24–7.

[29] Darnold made his professional debut on August 10, in the first preseason game against the Atlanta Falcons, where he finished with 96 passing yards and a touchdown as the Jets won 17–0.

[31] Darnold played his first regular season game on September 10, 2018, during Monday Night Football against the Detroit Lions, making him the youngest opening-day starting quarterback since the AFL–NFL merger.

[34] 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.

[42] During a rematch against the Dolphins in Week 9, Darnold threw four interceptions, finishing the game with 229 passing yards in a 13–6 Jets' loss.

[44] 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.

[45] 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.

[62] 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.

[69] 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.

[80] Darnold suffered a fractured scapula during the Panthers 24–6 loss against the Patriots which made him miss four to six weeks with a shoulder injury.

Coach Rhule told Carolina's Media, on Darnold's return from IR, he and Cam Newton would share play time.

[93] On August 23, 2023, Darnold was named the backup quarterback over Trey Lance, the team's third-overall selection from 2021, who was subsequently traded to the Dallas Cowboys the next day for a fourth-round pick.

With the top overall seed clinched, the 49ers elected to rest Brock Purdy and start Darnold in the regular season finale against the Los Angeles Rams.

Following the season, Darnold described his time with the 49ers as a valuable learning experience, citing the team's meticulous preparation and the influence of players like Brock Purdy and head coach Kyle Shanahan in reshaping his approach to the game.

[102][103] Darnold was named NFC Offensive Player of the Month, racking up 932 yards, a league-high 11 touchdowns, and a league-best 118.9 passer rating in September.

[104] Darnold led the Vikings to a 5–0 start before suffering consecutive losses to the Detroit Lions and Los Angeles Rams.

[106] After a shaky, three-interception outing against the Jacksonville Jaguars, Darnold bounced back the following week with three total touchdowns against the Tennessee Titans.

[109][110] In Week 14 against the Atlanta Falcons, Darnold had a career day, finishing with 347 yards and five touchdowns, along with setting the Vikings' single-game passer rating record.

[111] Darnold led another fourth quarter comeback in Week 16 against the Seattle Seahawks, finishing with three touchdowns as the Vikings win streak improved to eight games.

[113] In a Week 18 matchup against the Lions with the NFC's top seed at stake, Darnold completed 18-of-41 passes (41.9%) for 166 yards and no touchdowns as the Vikings lost 31–9.

[116] Though not regarded widely as a dual-threat quarterback, Darnold has been praised for his mobility in the pocket, which, when needed, allows him to escape pressure, extend plays and throw on the run.