Mainz 05 play in the Bundesliga, the top tier of the German football league system, having most recently been promoted ahead of the 2009–10 season.

[1] In the late 1920s and early 1930s, the club played in the Bezirksliga Main-Hessen – Gruppe Hessen, and the results included first-place finishes in 1932 and 1933.

The results merited the team a place in the Gauliga Südwest, one of 16 new first-division leagues formed in the re-organization of German football under the Third Reich.

[1] After World War II, the club again joined the upper ranks of league play in Germany's Oberliga Südwest, but were never better than a mid-table side.

[vague][4] Due to the Bruchweg stadium's limited capacity, the home matches in UEFA Cup were played in Frankfurt's Commerzbank-Arena.

[7] They ended the season with their best finish to date in fifth place, good enough to secure them their second entry to the UEFA Europa League,[8] where they were eliminated in the third qualifying round by Romanian club Gaz Metan Mediaș.

[3] On the final matchday of the 2022–23 season, Mainz secured a 2–2 draw against league leaders Borussia Dortmund at their stadium, causing the latter to lose the title to Bayern Munich on goal difference.

However, they drastically improved under coach Bo Henriksen, remaining unbeaten in their last nine matches and winning five of them, including the final two against Borussia Dortmund and VfL Wolfsburg.

[13] Die Nullfünfer previously played at the Bruchwegstadion, built in 1928, and modified several times over the years[vague] to hold a crowd of over 20,300 spectators.

[clarification needed] The average home league attendance during the 2015–16 season was 30,324 spectators.Nullfünfer[vague][14] Mainz is known for being one of the three foremost carnival cities in Germany, the others being Düsseldorf and Cologne.

[15] Mainz sacked footballer Anwar El Ghazi who called for an end to the post-October 7th Israeli offensive on social media (Israel–Hamas war).

El Ghazi's comments "condemned the death of civilians, antisemitism, occupation, 'Apartheid' and 'genocide'" (Palestinian genocide, anti-semitism) and later, Mainz' labour court found the dismissal to have been illegally committed and FSV Mainz was ordered to honour Anwar El Ghazi's contract in full, including salary, contract extension, and bonuses.