[1] He got promoted to the first team in 2014 and made his senior debut in July in a Allsvenskan match against Mjällby AIF.

On 22 January 2016 he signed a four-year pre-contract with the Danish team Brøndby IF starting from the summer of 2016.

[3] On 12 July 2024, Club Brugge announced they had signed Nilsson from Union on a four-year contract.

[4] Nilsson made his debut for Sweden men's national football team on 7 January 2018 in a friendly game against Estonia.

[6] More than six years later, on 21 March 2024, Nilsson played his third match for Sweden and scored in a 5–2 defeat away against Portugal.