Igor made his professional debut for Liefering on 22 July 2016, starting in a 1–0 Austrian First League home win against SV Horn.[3] After being a regular starter, he made his first team debut the following 28 May, playing the full 90 minutes in a 1–0 home defeat of SC Rheindorf Altach.
Igor was promoted to Red Bull Salzburg's main squad on 26 May 2017,[4] but continued to appear mainly with the B-team. On 7 January 2018, he was loaned to fellow top tier club Wolfsberger AC, until June.[5]
On 2 July 2018, Igor moved to Austria Wien also in the first division, on a season-long loan deal.[6]
On 26 June 2019, Igor signed to Italian Serie A club SPAL a contract until 2023.[7]
On 31 January 2020, Igor joined Fiorentina on a two-year loan with an obligation to buy.[8]
On 26 July 2023, Premier League side Brighton & Hove Albion announced the signing of Igor on a four-year deal,[9] for a reported fee of €17 million.[10] Igor made his Brighton debut on 8 October 2023, playing sixty-three minutes in a 2–2 home draw against Liverpool in the Premier League.[11]