Grünke joined the Young Liberals and the FDP in 2017. From 2019 to 2021 he was chairman of the FDP city association in Tübingen.
Grünke ran for office in the 2021 German federal election in the Tübingen constituency, but initially missed out on a place in the Bundestag. He replaced Michael Theurer in the Bundestag on 2 September 2024.[2] He sits on the Committee on the Environment, Nature Conservation, Nuclear Safety and Consumer Protection, the Committee on Education, Research and Technology Assessment and the Committee of Inquiry into the Nuclear Phase-out.[3]