He played Pop Warner football in the same Florida league with Ravens quarterback Lamar Jackson, though the two were on different teams.

As an 11th grader Brown ran the 100 meters in a time of 11.53 seconds at the Florida High Schools Athletic Association's 4A District 13 regional championship track meet.

[2] He transferred to Chaminade-Madonna College Preparatory School where in addition to playing football he also ran track, improving his 100-meter time to 10.90 seconds and posting a personal-best time of 21.94 seconds in the 200 meters at the Florida High Schools Athletic Association's 2A District 15 regional championship track meet.

Because California Junior colleges do not offer sports scholarships, Brown worked at Six Flags Magic Mountain to make ends meet.

[6] After a year at College of the Canyons, Brown received several Division 1 scholarship offers, committing to Oklahoma.

[8] On January 2, 2019, Brown announced that he would forgo his final year of eligibility to declare for the 2019 NFL draft.

[16] Brown made his regular season debut against the Miami Dolphins in Week 1, recording four receptions, 147 receiving yards and two touchdowns.

[17] Despite playing only 14 snaps, Brown became the first player in NFL history to score two touchdowns of 40 yards or more in his first game.

[21] Brown finished 2019 as the Ravens' second leading receiver behind tight end Mark Andrews.

[22] In his playoff debut, Brown led both teams with seven catches for 126 receiving yards in a 12–28 Divisional Round loss to the Tennessee Titans.

[31] In the AFC Wild Card Round against the Titans, Brown had seven receptions for 109 yards as the Ravens won 20–13.

[35] In Week 5 against the Indianapolis Colts, Brown caught a career-high nine receptions for 125 yards and two touchdowns, including the game-winner, as the Ravens again rallied to win in overtime 31–25.

On August 3, 2022, Brown was arrested and charged with criminal speeding (going 126 mph) in north Phoenix and was booked into the Maricopa County Jail.