Grau became a member of the Bundestag in the 2021 elections, representing the Ludwigshafen/Frankenthal district.[1] In parliament, he has since been serving on the Health Committee and the Committee on the Environment, Nature Conservation, Nuclear Safety and Consumer Protection.[1]
In addition to his committee assignments, Grau has been one of the founding members of a cross-party group promoting a One Health approach since 2022.[3]