The club had 18,200 members as of January 1, 2020. The Rheinhessen side were promoted to the Bundesliga for the first time in 2004 and stayed until 2007. After a brief return to the second division, they came back up in 2009 and have remained in the top flight ever since. Mainz 05 play in the Rhineland-Palatinate state capital and compete in Germany's top league as the only club from that federal state.