[1] The first match played under that name comes the 16th of March of that same year, when Proleter beats city-rivals Mladost by five goals to nil.

Proleter moved to current Gradski vrt stadium in autumn 1958 and changed its name to Slavonija as part of the unifying process of the boxing, athletics and Olympic lifting club in a newly founded sports association in 1962.

In 1970, Osijek wins the 2nd North League championship, however, Borac Banja Luka beat them in the promotion play-offs.

NK Zagreb proved victorious on the day, winning via a penalty shoot-out following a 2–2 draw after 90 minutes, Osijek denied promotion for a third time in four years.

In 1977, NK Osijek finally secured its return to the top flight by taking out the league championship.

In 1989, the team placed 8th with Davor Šuker leading the line for the side scoring 18 goals, taking out the league's best goalscorer award.

The greats of NK Osijek during that time were–a part from Špehar–Žitnjak, Lulić, Beljan, Ergović, Rupnik, Beširević, Bičanić and Labak.

A year later, West Ham United was playing away in Gradski vrt, headed by Frank Lampard, Rio Ferdinand, Trevor Sinclair, Paolo Di Canio, Paulo Wanchope and Igor Štimac.

In the 2001–02 UEFA Cup, Osijek progressed past Dinaburg on away goals, beat Gorica in the first round, but then lost 3–5 to AEK Athens.

On the final match day, Josip Barišić managed to score and keep Osijek afloat against Hrvatski dragovoljac.

[6] The 4th-place finish led to Osijek participating in the qualifying phase of the 2017–18 UEFA Europa League; with the club staging an extremely successful run to the play-off round, beating Santa Coloma, Luzern and PSV, the former champions of Europe, who won the 1987–88 edition.

Despite being eliminated, Osijek were praised and congratulated by Croatian press, fans and media for their historic run.

Osijek beat Petrocub Hîncești 2–1 at home after drawing the first leg in Moldova 1–1, and faced Rangers in the second qualifying round of the 2018–19 UEFA Europa League.

[17] On 9 September 2020, it was announced that Lőrinc Mészáros was no longer the formal co-owner of the club, with the private investment fund BETA taking over his shares in NK OS d.o.o.

The reason being that Mészáros was also the owner of Puskás Akadémia FC, and UEFA rules forbade two clubs owned by the same person from participating in European competitions, should they have both qualified.

In April 2018, NK Osijek president Ivan Meštrović released plans for the new Pampas Stadium.

The fan club of NK Osijek is called Kohorta (cohort, named after the Roman army unit composed of 360 soldiers).

[21] The Slavonian derby match is between the two largest Croatian football clubs from eastern Croatia, Osijek and Cibalia.

Rijeka and Osijek are with Dinamo Zagreb and Hajduk Split the only four clubs that have never been relegated from the Croatian First League.

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.