[1][2] He also ran track and played basketball and soccer as a youth before starting his freshman year at Cajon High School in 2015.

[3][4] Daniels, initially needing a medical note to play due to being considered undersized for the position at 125 pounds (57 kilograms), started on Cajon's varsity team as a freshman.

He led the team to the CIF Southern Section (CIF-SS) Inland Division playoffs that year before being eliminated in the semifinals.

[9] He was named the men's recipient of the Ken Hubbs Award, given annually the top high school athletes in the greater San Bernardino area, following the season.

[3][11] He participated in the 2018 Elite 11 quarterback skills competition, sitting out of the finals due to a practice injury, and passed for a game-winning touchdown in the 2019 Under Armour High School All-America Game.

[29] Daniels, playing on a sprained ankle, left the game after being sacked by Jalen Carter late in the second quarter.

[29][30] He returned for the 2023 Citrus Bowl, catching a touchdown pass from wide receiver Malik Nabers in a 63–7 win over the Purdue Boilermakers.

[31] Daniels was named a semifinalist for the Davey O'Brien Award and voted the team's most valuable player after accounting for 28 touchdowns and nearly 3,800 total yards.

[37] Daniels won the 2023 Heisman Trophy and other player of the year awards after setting the FBS single-season passer rating record with nearly 5,000 total yards gained, which lead the NCAA that season, with 40 passing and 10 rushing touchdowns.

[53][54] Daniels suffered a rib cartilage injury on the opening drive against the Carolina Panthers in October and sat out the remainder of the game.

[62] The Commanders, having their first postseason win in nearly two decades, saw victories over the Tampa Bay Buccaneers and Detroit Lions in the 2024–25 NFL playoffs before being eliminated by the Philadelphia Eagles in the NFC Championship Game.

[2][100][101] He uses virtual reality (VR) as part of his training, using software designed by German developer Cognilize that incorporates custom game plans and allows for speed adjustments and opposing players, teams, and their stadiums to be represented.

[104] Daniels warms up before games with a basketball; he learned the routine from childhood friend C. J. Stroud and cites it as helpful preparation as footballs feel smaller and lighter afterwards.

[4][109][110] In college, he signed name, image, and likeness (NIL) deals with Raising Cane's, Powerade, Beats by Dre, and Urban Outfitters.

[116] Daniels threw the ceremonial first pitch at a Washington Nationals baseball game in June 2024; the following month he, alongside Livvy Dunne and Lil Wayne, presented the Best Play Award to Lamar Jackson at the 2024 ESPYs.