On 27 November 1903, Wilhelm Hauschild wrote a letter – signed by 180 of his fellow workers – to his employer, the Friedrich Bayer and Co., seeking the company's support in starting a sports club.

[12] The company agreed to support the initiative, and on 1 July 1904 Turn- und Spielverein Bayer 04 Leverkusen was founded as a works team.

SV Bayer 04 Leverkusen took with them the club's traditional colours of red and black, with the gymnasts adopting blue and yellow.

The next year saw the club in the Regionalliga West, tier II, where their performances over the next few seasons left them well down[vague] the league table.

By the mid-1980s, SV Bayer 04 Leverkusen had become established in the upper half of the league table and was well-established there by the end of the decade.

It was during this time, in 1984, that the two halves of the club that had parted ways over a half century earlier were re-united as TSV Bayer 04 Leverkusen e.V.

Down 0–3 to Espanyol after the first leg of the final, Bayer Leverkusen drew even in the return match and then won the title on penalty kicks, 3–2.

[citation needed] Calmund also established contacts in Brazilian football, befriending Juan Figer, one of Brazil's most powerful player agents.

The club won its next major honour in 1993 with a 1–0 win in the DFB-Pokal final against Hertha BSC second team (amateur squad) on 12 June 1993.

offensive style of play under new coach Christoph Daum, who was also helped by the signing of players such as Lúcio, Emerson, Zé Roberto and Michael Ballack.

Early in 2005, Augenthaler was fired as manager after the club got off[tone] to its worst Bundesliga start in over 20 years, with only one win in its first four league matches and a 0–1 home loss to CSKA Sofia in the first leg of its UEFA Cup match-up.

[citation needed] Bayer Leverkusen also lost a lot[quantify] of its support towards the end of the season: in the 1–2 home loss against Hertha BSC, the Leverkusen fans caused much commotion, with fans chanting for the sacking of Skibbe, while some Ultras, who had seen enough,[vague] set fire to their jerseys and threw them onto the field.

[30][33] Leverkusen finished the season in ninth place in the Bundesliga table and Labbadia moved to Hamburger SV in June 2009.

However, Heynckes decided not to extend his contract and left Bayer Leverkusen in the 2011 close season to take over at Bayern Munich for a third time.

In the 2019–20 UEFA Europa League, Leverkusen reached the quarter-finals for the first time since 2008,[37] but were ultimately[vague] knocked out by Inter Milan in a 2–1 loss.

In October 2022, with the club in the relegation zone, Leverkusen appointed Xabi Alonso as head coach in his first senior managerial role; he went on to guide the team to safety and a sixth-placed finish.

[38] In 2023–24, Alonso's first full season in charge, Leverkusen achieved significant domestic and European milestones, bolstered by effective squad building and strategic signings including Switzerland captain Granit Xhaka, Victor Boniface, Jonas Hofmann, Alejandro Grimaldo, and Matej Kovar.

[39] By early 2024, they had set a new club record for the longest unbeaten start to a season followed by breaking the Bundesliga record (formerly held by Hamburger SV since the 1982–83 season) for the longest unbeaten run by a club in all competitions with 26 games unbeaten[40] followed by breaking the European record of the European "top 5 leagues" (Bundesliga, Premier League, Primera División, Ligue 1, Serie A) set by Juventus in 2011 and 2012 of 43 cross-competitive compulsory games in a row without defeat.

[41][42] On 14 April 2024, Leverkusen were crowned Bundesliga champions for the first time ever after beating Werder Bremen 5–0, ending Bayern Munich's run of 11 successive league titles.

[47][48] Their unbeaten streak ended in their 52nd game of the season with a hat trick by Ademola Lookman giving them a 3–0 loss to Atalanta in the Europa League final.

In contrast to many other German football clubs, which hold close ties to their working-class roots, Bayer Leverkusen strives for a clean, family-friendly image.

Other clubs, including PSV, FC Carl Zeiss Jena and Sochaux, share a similar reputation of being works teams.

[59][60] As distinguished from the various Red Bull teams (Salzburg, New York and Leipzig) which were established or redefined in the early 21st century primarily for commercial reasons, the formation of Bayer Leverkusen was motivated by the idea of promoting the living conditions of local factory workers early in the 20th century.