[4] He made his professional debut for Feyenoord in a 2–1 UEFA Champions League win against Napoli on 6 December 2017, wherein he played the full 90 minutes.

[9] On 5 July 2022, Malacia signed a four-year contract with Premier League club Manchester United, with the option of a further year.

[12] On 7 August, Malacia made his club debut as a substitute in a 2–1 home loss against Brighton & Hove Albion in the Premier League.

[15] Malacia started United's final Premier League match of the 2022–23 season on 28 May 2023,[16] which proved to be his last appearance for over a calendar year.

[18] He followed this up by making his first-team return sixteen days later, playing 45 minutes in the Europa League against Bodø/Glimt,[19] for which he was praised by manager Ruben Amorim.

[29] On 27 August 2021, Malacia received his first call-up for the Netherlands national football team for the 2022 FIFA World Cup qualification matches against Norway, Montenegro and Turkey.