Sarah Steinemer completed her musical theatre training in the summer of 2019. During this time, she was already part of the cast of the productions »Kiss Me, Kate«, »Die Fledermaus«, and »Footloose« at the Staatstheater Darmstadt. She then took on the lead role of Charlotte Brontë in the musical »Schwestern im Geiste« at the Mainzer Kammerspiele. From 2019 to 2020, Sarah Steinemer was part of the ensemble of »The Producers« at the Staatstheater Mainz. In 2020, she danced in the opera »Anna Nicole« at the Staatstheater Wiesbaden. From 2021 to 2022, she played the roles of Ilonka and Hermence and was Dance Captain in »Ball im Savoy« at the Staatstheater Darmstadt.
Further productions followed, including »Victor/Victoria« at the Staatstheater Mainz. She appeared as Lulu in »Cabaret« at the Neue Bühne Senftenberg and as cover Kiki, as well as in the ensemble of »Flashdance« at the Walensee Stage in Walenstadt (Switzerland). In 2024, she performed at the Staatstheater Darmstadt in »Jekyll & Hyde« and »Im weißen Rössl«, once again as Dance Captain.
During the 2023/24 season, she was part of the ensemble for the production »Chess« at the Oldenburgisches Staatstheater, and in 2024/25, she played one of the Kit Kat Girls in »Cabaret«.