On 26 July 2021, Van der Avert signed a two-year contract with Eerste Divisie club Dordrecht after a successful trial, in which he impressed in pre-season friendlies against ASWH and Almere City.[2] He made his competitive debut on 20 August, replacing Seydine N'Diaye in the 63rd minute of a 2–2 home draw against Jong Utrecht.[5]
Van der Avert quickly evolved into a starter for the team at centre-back.[6] On 20 October 2023, he scored his first professional goal in a 4–0 league victory against Jong Ajax, heading in a Jari Schuurman corner-kick; his third assist of the game.[7]