Horn spent his youth career at
VfL Wolfsburg, where he was promoted to the first team during the
2016–17 season. In June 2017, Horn joined
1. FC Köln who had recently qualified for the
UEFA Europa League. On 15 August 2019, Horn joined
Hannover 96 on a loan deal until the end of 2019–20 season. After
Timo Hübers was infected with
COVID-19, all Hannover 96 players were tested, but only Horn was tested positive. According to the club, his case had no connection to Hübers' case. On 25 July 2022, Horn signed a two-year deal with
VfL Bochum. On 7 January 2023, he moved on loan to
1. FC Nürnberg in
2. Bundesliga. On 29 June 2023, Horn signed a permanent contract with
1. FC Nürnberg. On 2 August 2024, Horn moved on loan to
St. Louis City until 30 June 2025, with an option to buy. On 20 June 2025, Horn joined
SK Rapid Wien in Austria on a two-year deal. ==Career statistics==