Promi Big Brother 2021, also known as Promi Big Brother 9, is the ninth season of the German reality television series Promi Big Brother. The show began airing on 6 August 2021 on Sat.1 and will end after 24 days on 27 August 2021, making it the second longest celebrity season to date. It is the ninth celebrity season and the tenth season of Big Brother in total to air on Sat.1 to date. Jochen Schropp and Marlene Lufen both returned as hosts of the show.