Due to a lack of football pitches in Stockholm, several other clubs proposed to merge with Hammarby IF to get access to the stadium.

[15][16] The club played its first competitive game two days later, and won 5–0 against Västerås SK in the "Östsvenska serien", a local league, with Ragnar Gunnarsson scoring the inaugural goal.

[19] In 1920, Hammarby first competed in the Svenska Serien, by then the highest league in Swedish football, with key players like goalkeeper Victor Olsson, defender Gösta Wihlborg and forward Gustav Björk.

Several star players emigrated to the United States,[21] transferred to other clubs or opted to instead play ice hockey for Hammarby.

[23][24] Instead, Hammarby got promoted in 1938–39, where they knocked out IFK Norrköping following outstanding performances from goalkeeper and star player Sven Bergqvist.

With star players Kenneth Ohlsson and Ronnie Hellström, and with a crowd that tried out supporter songs for the first time, the club went through the autumn half undefeated and finished in fifth place, its best showing in Allsvenskan.

After defeating Örgryte in the quarter-finals, and coming back from a 1–3 deficit to beat Elfsborg 4–3 in the semi-finals, Hammarby was in the final against IFK Göteborg.

Prior to the 2001 Allsvenskan season, the club had financially tough times, leading experts to conclude that the team was weak, and one journalist predicted a last place finish.

In the 2010 Svenska Cupen, Hammarby fared better, winning against multiple Allsvenskan opponents, until the finals where the team lost 0–1 to Helsingborgs IF.

This was followed up with a 2–0 win in the season opener against BK Häcken, and in the fourth round Hammarby defeated their other local rivals Djurgårdens IF with 2–1.

The summer was, however, tougher for the club, with Hammarby playing 10 consecutive league games without winning, before managing to defeat Falkenbergs FF at home with 3–0.

[30] Hammarby IF won the 2020–21 Svenska Cupen, their first title in the main domestic cup, through a 5–4 win on penalties (0–0 after full-time) against BK Häcken in the final.

[31][32] On 11 June 2021, Hammarby decided to terminate manager Stefan Billborn's contract, with the club placed 8th in the 2021 Allsvenskan table after eight rounds.

[34] Under the leadership of Milojević, Hammarby nearly reached the group stages of the first edition of the UEFA Conference League, only being defeated on penalties by FC Basel in the playoff.

It drew inspiration from two other competing rowing clubs in Stockholm that used two blue and two red lines respectively on a white flag, but chose the colour green to represent "hope".

A limited company called Hammarby Fotboll AB was founded, in which the parent football club owns a majority stake.

In Sweden, all sport teams in the league systems are regulated to be non-profit associations, which means that a majority of the voting rights, according to the "51 percent-rule", is controlled by the members of the club.

[43] Anschutz Entertainment Group (AEG), the founder and owner of Major League Soccer club LA Galaxy, was the biggest external investor and minority shareholder of Hammarby Fotboll AB between 2001 and 2019.

[44] On 27 November 2019, it was announced that Zlatan Ibrahimović, widely regarded to be the greatest Swedish football player of all time, had acquired 23.5 percent of the outstanding shares in Hammarby, which meant that AEG reduced their stake by half.

[55][56] According to a 2016 poll, a large part of the club's fan base tends to support left-wing politics compared to those of their local rivals AIK and Djurgården.

Since 2014, Hammarby has had the highest average attendance in Scandinavia, except for in 2020 and 2021 when matches were partly played behind closed doors due to the COVID-19 pandemic.

In 1942, the popular recording artist Alice Babs released a version of the song Vårat gäng ("Our Gang") with new, Hammarby-related lyrics.

[67] Critically acclaimed author Per Anders Fogelström, who rose to fame with his 1960 novel Mina drömmars stad ("City of My Dreams"), with a narrative that follows a group of working-class people in Södermalm between 1860 and 1880, was also a supporter of Hammarby.

[68] In 1962, writer and illustrator Stig "Slas" Claesson penned a short story, Supportern ("The Supporter"), about his love for the club.

[69] Hollywood actors Alexander Skarsgård and Joel Kinnaman are supporters of Hammarby, and have acted in several skits to promote the club.

[55][76] Note: Flags indicate national team as defined under FIFA eligibility rules; some limited exceptions apply.

Note: Flags indicate national team as defined under FIFA eligibility rules; some limited exceptions apply.

Note: Flags indicate national team as defined under FIFA eligibility rules; some limited exceptions apply.

Note: Flags indicate national team as defined under FIFA eligibility rules; some limited exceptions apply.

Playing their home games in Eriksdalshallen, Hammarby competed in the Swedish second tier, Division 1 Södra Svealand, during their inaugural season.