He played his first three seasons of college football for the Auburn Tigers, winning SEC Freshman of the Year in 2019.

Nix was selected by the Broncos in the first round of the 2024 NFL draft, becoming their starter during his rookie season and leading them to their first playoff appearance since 2015.

[3] He was rated the top dual-threat quarterback of his class and committed to play college football at Auburn University.

[16] On December 12, 2021, Nix announced he was entering the transfer portal, describing himself as "miserable" while playing under Auburn head coach Bryan Harsin who had been hired in 2021.

[22] The season saw ranked victories over BYU, UCLA, and Utah before culminating in a 28–27 win over North Carolina in the Holiday Bowl.

[27] Nix finished third place in the Heisman Trophy vote behind Jayden Daniels and Michael Penix Jr..[28] Following his final collegiate game in the Fiesta Bowl against Liberty, he broke Mac Jones's previous record for the highest single season completion percentage at 77.45%.

[36] In his NFL debut against Seattle, Nix completed 26 of 42 passes for 138 yards, two interceptions, and a rushing touchdown in a 26–20 loss.

[38] Nix earned his first win in Week 3 against the Tampa Bay Buccaneers, throwing for 216 yards, a rushing touchdown, and no interceptions in a 26–7 victory.

[39] In Week 4, he recorded his first career passing touchdown and led the Broncos to a 10–9 upset victory of the New York Jets, with Nix not allowing a turnover or sack for the second consecutive game.

[42] He capped the month with 284 passing yards, four total touchdowns, and a 75.7% completion rate in Week 8 against the Carolina Panthers, setting a new franchise record with five wins as a rookie.

[47][48] Nix led the Broncos to victories in their next three games to reach 9–5, but losses to the Los Angeles Chargers and Cincinnati Bengals put their playoff hopes in jeopardy.

[49][50] Needing a win in the final week, Nix went 26-of-29 with 321 yards and four touchdowns in a 38–0 victory over the Chiefs to clinch the Broncos' first playoff berth since 2015.