After making 159 appearances and scoring twelve goals for the club, Dendoncker moved to fellow Premier League side Aston Villa in September 2022 for an undisclosed fee.

[4] He made his professional debut on 21 July in the 2013 Belgian Super Cup, replacing Dennis Praet for the final nine minutes of the 1–0 win over Genk at the Constant Vanden Stock Stadium.

[11] He also played all 16 games in their European campaign that season, which ended with elimination by eventual winners Manchester United in the quarter-finals of the UEFA Europa League.

[13] He made his debut on 28 August in the second round of the EFL Cup away to Sheffield Wednesday (2–0 victory), with coach Nuno Espírito Santo making nine changes from the previous game.

[14] In late September, The Football Association rejected the obligatory purchase clause in Dendoncker's Wolves contract and made his deal permanent for €15 million.

[18] On 4 May he scored the only goal of a home win over Fulham, which enabled Wolves to make the Europa League as a result of Watford losing the cup final.

[24][25] He made his 100th competitive appearance for the club in an FA Cup 4th Round tie away to non-league Chorley the following 22 January, a game Wolves won 1–0.

[28] On 1 September 2022, Dendoncker moved to fellow West Midlands-based Premier League club Aston Villa for a fee of around £13 million.

[30] He was mainly used as a substitute in his first season, and missed out on games altogether, and manager Unai Emery said that it was because of "a problem at home"; he was absent from all of March 2023 with a hand injury.

[37] Dendoncker was first called up for the Belgium national football team on 22 May 2015 by manager Marc Wilmots, along with his Anderlecht teammate Youri Tielemans.

[44] At the 2022 FIFA World Cup, he started Belgium's opening match against Canada in a three-man defence alongside the experienced Jan Vertonghen and Toby Alderweireld in a 1–0 win,[45] and was dropped from the next game, a 2–0 defeat to Morocco.

[50] Dendoncker moved to Brussels to play for Anderlecht while in their under-15 team and suffered from homesickness while adjusting to the difference between a largely white rural setting and a diverse urban environment.