Willi Geitmann was born in 2002 in Berlin and grew up in Oberkrämer, Brandenburg. He made his on-screen debut in 2019 with a supporting role as a student in the television film "Das Unwort", starring Iris Berben. In 2021, he was cast in a leading role in the feature film "Jenseits der blauen Grenze" ("Beyond the Blue Border"), where he plays the best friend of a young competitive swimmer from the GDR who comes under the scrutiny of the Stasi and wishes to flee to the West. Before this film premiered, Geitmann took various acting classes and workshops starting in 2022, including sessions at The PIT improv theater in New York City, with Gregory Berger in Los Angeles, and with Teresa Harder in Berlin.

In January 2024, "Jenseits der blauen Grenze" premiered at the Max Ophüls Prize Film Festival and received several awards, including the Best Acting Newcomer award for Geitmann. The film was released in theaters in the fall of 2024.