Bayer 04 Leverkusen's story began not on a pitch, but inside a factory. The club was founded on 1 July 1904 in Leverkusen as a gymnastics association for employees of the Bayer pharmaceutical company, which is still the source of its nickname "Die Werkself" — "the works XI." A football section followed in 1907, and the club has maintained close ties with the company ever since; Bayer AG remains its owner to this day, an exception to German football's usual "50+1" ownership rule.
Since 1958, Bayer has played its home matches at the ground now known as the BayArena, originally named Ulrich-Haberland-Stadion after a former chairman of Bayer AG. Following extensive redevelopment, the stadium was renamed in 1998 and now has a capacity of 30,210.
For decades, the club was seen as football's eternal nearly-man, earning it the ironic nickname "Neverkusen" after a string of painful near-misses, including the 2002 UEFA Champions League final, where a side featuring Michael Ballack and Lúcio lost 2–1 to Real Madrid following Zinedine Zidane's legendary volley. Earlier, in 1988, Bayer had claimed its first international trophy by winning the UEFA Cup.
The greatest chapter in the club's history, however, was written in the remarkable 2023/24 season, when the team led by Xabi Alonso won its first-ever German league title, completing the entire Bundesliga campaign without a single defeat — the first club in the league's history to do so. Bayer 04 also lifted the DFB-Pokal that season, completing its first-ever domestic double, and reached the UEFA Europa League final, where it was beaten by Atalanta. Key roles in that unforgettable season were played by Florian Wirtz, Victor Boniface, Granit Xhaka, and Jeremie Frimpong, joining earlier club legends such as Ballack, Lúcio, Zé Roberto, Bernd Schneider, and Rudi Völler among the greatest figures in Werkself history.
The philosophy of Bayer 04 Leverkusen rests on a combination of advanced scouting, consistent youth development, and attractive attacking football, which has allowed the club to compete year after year with Europe's leading teams despite operating on a far smaller budget than the continent's giants.