By SABC Sport
9th July 2023
The USA international, 22, made 36 Premier League appearances for Leeds last season after joining from Red Bull Salzburg for a fee close to £25million in the summer of 2022.
Leeds said: "Leeds United midfielder Brenden Aaronson has (on Sunday) joined Union Berlin on loan until the end of the 2023/24 season.
"We would like to wish Brenden good luck during his time at the Stadion An der Alten Forsterei."
Aaronsen, who scored one goal in 40 appearances in all competitions for Leeds, is the third player who featured for them in the Premier League last season to have departed on a season-long loan following relegation.
Diego Llorente and fellow defender Robin Koch joined Roma and Eintracht Frankfurt respectively in similar deals earlier this week.
Leeds have appointed former Norwich boss Daniel Farke as their head coach since their three-year stay in the top flight was ended in May.