The 2020–21 NK Osijek season was the club's 107th season in existence and the 30th consecutive season in the top flight of Croatian football.

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

Players may hold more than one non-FIFA nationality.

Total Spending: €4,400,000 Total Income: €7,810,000 Net Income: €3,410,000 Last updated: 23 May 2021 Source: Soccerway Last updated: 23 May 2021.

Source: Prva HNL Source: Croatian Football Federation Source: Croatian Football Federation[35] Source: uefa.com Updated 23 May 2021 Source: Competitive matches Source: Competitive matches