[3] During his time at YSC Academy, Aaronson had played for Union's youth teams before committing to Indiana University and signing an amateur contract with Bethlehem Steel FC.

[8] Aaronson made 21 appearances for Steel FC and scored his first goal for the professional side against Atlanta United 2.

[10] On March 17, 2019, the homegrown player scored his first professional goal in his MLS debut, helping Philadelphia tie against Atlanta United.

[15] After persistent rumors, it was announced on October 16, 2020, that Aaronson would join Red Bull Salzburg effective January 2021 after the MLS season ended.

[25] He made his senior league debut for Leeds as part of the starting eleven in their season opener on August 6, with a 2–1 home win over Wolverhampton Wanderers.

[27] On July 9, 2023, following Leeds' relegation from the Premier League, Aaronson joined Bundesliga side Union Berlin on loan for the 2023–24 season.

[34][35][36][37] His younger brother Paxten Aaronson is also a professional soccer player and plays for FC Utrecht, on loan from Eintracht Frankfurt.