Finn Dahmen was born on March 27, 1998, in Wiesbaden, Germany. He began his football journey at the youth academies of FC Bierstadt and Eintracht Frankfurt, eventually joining Mainz 05's youth system in 2008. Dahmen made his professional debut on April 11, 2018, while playing for Mainz 05 II, where he notably scored a goal with a backheel kick, a rare feat for a goalkeeper. He stepped up to the first team on January 3, 2021, facing Bayern Munich in the Bundesliga.
Dahmen has established a reputation as an agile and composed goalkeeper, adept at shot-stopping and organizing his defense. As of June 1, 2023, he transferred to FC Augsburg, aiming to further his career in the top tier of German football.
Though he represented various German youth national teams, including participating in the 2015 FIFA U-17 World Cup, he has not yet made his senior national team debut.