The campaign has been launched by the magazine 11Freunde (11 Friends) and includes statements from several Bundesliga stars, including Hertha Berlin's Dedryck Boyata, Borussia Mönchengladbach's Christoph Kramer and FC Köln's Jonas Hector.
The latest issue of the magazine features a number of different cover stars holding signs that read: "You can count on us!" Fans have also been sharing images with the same message on social media.
"Even in 2021, there will not be a single openly homosexual footballer in the German men's professional leagues," said a statement from the players backing the campaign.
"The fear of being attacked and ostracized after coming out and of jeopardizing one's career as a professional footballer is apparently still so great that gay footballers believe they have to hide their sexuality.