Early career Maatsen joined
Feyenoord's academy at the age of seven, but was allegedly dropped for being too small. He moved to
Sparta Rotterdam and then
PSV Eindhoven, before joining
Chelsea in 2018.
Chelsea On 25 September 2019, he made his debut for the London club as a substitute in a 7–1
EFL Cup victory over
Grimsby Town.
Loan to Charlton Athletic On 13 October 2020, Maatsen joined
Charlton Athletic on a season-long loan. On 20 October, he made his league debut for Charlton, coming off the bench as a second-half substitute in the side's 1–0 win over
Blackpool. He scored his first senior goal on 2 April 2021 in a 1–0 away win over
Doncaster Rovers.
Loan to Coventry On 30 July 2021, Maatsen joined
Coventry City on loan. On 2 October 2021, he scored his first goal for Coventry in a match against
Fulham, helping his team to a 4–1 victory. Overall, Maatsen made 40 league appearances for the
Sky Blues and scored three goals during the
2021–22 season.
Loan to Burnley On 15 July 2022, Maatsen joined
Burnley on a season-long loan. He made his debut in the first round of the
2022–23 EFL Championship against
Huddersfield Town, where he also scored the only goal of the game in a 1–0 win. Following his impressive performances, Maatsen was named the
EFL Championship Player of the Month for January 2023. His team eventually won the league and promotion to the Premier League, with Maatsen being included in the Championship Team of the Season as the best left-back.
Loan to Borussia Dortmund On 12 January 2024, Maatsen signed a contract extension with Chelsea until 2026 and joined
Borussia Dortmund on a six-month loan. On 16 April, he scored his first
Champions League goal in a 4–2 win against
Atlético Madrid in the
quarter-finals second leg, helping his team progress to the semi-finals. Borussia eventually reached the
final, where Maatsen started the match and made a misplaced pass that led to
Real Madrid's second goal in a 2–0 defeat at
Wembley Stadium. However, he was named in the competition's Team of the Season as the best left-back.
Aston Villa On 28 June 2024, 22-year-old Maatsen signed for fellow Premier League club
Aston Villa for an undisclosed fee, reported to be £37.5 million, signing a six-year contract. On 17 August 2024, Maatsen made his Aston Villa debut as a substitute in a 2–1 opening day victory over
West Ham United. On 12 March 2025, Maatsen scored his first goal for Aston Villa during a 3–0 win against
Club Brugge in the
UEFA Champions League round of 16. ==International career==