Mats Wieffer

Excelsior In June 2020, Wieffer joined Excelsior on a free transfer, signing a three-year contract with the club. He made his debut for Excelsior on 29 August 2020, replacing Mitchell van Rooijen in a 1–6 win against Jong PSV in the Eerste Divisie. He was sent off with a red card in the league game against FC Eindhoven on 9 October 2020, which ended in a 1–1 draw.

On 5 February 2021, Wieffer scored his first goal in professional football in a 0–2 win against Volendam. He was named Excelsior Player of the Year after his first season at the club, winning 26% of the votes. On 29 May 2022, he scored in the penalty shoot-out as Excelsior beat ADO Den Haag in the final of the play-offs to promote to the Eredivisie

Feyenoord

In June 2022, Wieffer moved to Feyenoord on a four-year contract. After getting injured in a friendly against Red Bull Salzburg in pre-season, he made his debut for Feyenoord and in European football on 8 September 2022, coming on as a substitute for Javairô Dilrosun in a 4–2 defeat against Lazio in the UEFA Europa League. Three days later, he replaced Dilrosun during a 3–0 victory against Sparta Rotterdam to make his Eredivisie debut.

On 13 January 2023, Wieffer scored his first goal for the club while also providing an assist in a 3–1 cup win over PEC Zwolle, what was his first start for the club. He was named Feyenoord Player of the Month for January 2023 and February 2023. On 13 April 2023, Wieffer scored his first goal in a European club competition, scoring the only goal in a 1–0 win over Roma in the quarter-finals of the UEFA Europa League. He assisted goals of Oussama Idrissi and Igor Paixão on 14 May 2023 as Feyenoord beat Go Ahead Eagles 3–0 to secure its sixteenth Eredivisie title.

On 4 August 2023, Wieffer played the full game as Feyenoord lost the Johan Cruyff Shield 0–1 to PSV Eindhoven. Wieffer made his UEFA Champions League debut on 19 September 2023, in a 2–0 win against Celtic. He scored his first goal in the competition on 28 November 2023, during a 1–3 defeat against Atlético Madrid. Ahead of the KNVB Cup final on 21 April 2024, Wieffer suffered a thigh injury, ruling him out for the remainder of the season. Feyenoord went on beat NEC 1–0 in the cup final and finish in second place in the Eredivisie. During his time at Feyenoord, Wieffer played 54 league games, in which Feyenoord averaged 2.52 points, recording a joint-record for players in the Eredivisie with over 50 games played.

Brighton and Hove Albion On 5 July 2024, Wieffer joined Premier League club Brighton & Hove Albion, signing a contract until June 2029. With a reported fee of €30 million, it became Feyenoord's most expensive outgoing transfer of all-time. He made his Premier League debut in Brighton's opening match against Everton on 17 August 2024, where he registered an assist as the Seagulls would go on to win 3–0. On 11 April 2026, he scored two goals in a game for the first time in his career as Brighton won 2-0 at Burnley.

International career On 17 March 2023, Wieffer received his first call-up to the Netherlands senior national team for the Euro 2024 qualifying matches against France and Gibraltar. He made his debut on 27 March as a starter in a 3–0 win over Gibraltar. On 21 November 2023, Wieffer scored his first senior international goal in the Netherlands' 6–0 win against Gibraltar. A thigh injury ruled him out from participating in UEFA Euro 2024.

On 27 May 2026, Wieffer was named in the Netherlands' squad for the 2026 FIFA World Cup.

Style of play Wieffer said that he prefers to play as a number six, but is also able to play box-to-box. He has been praised for his mentality, interceptions, passing and energy and called "the missing link between Feyenoord's offence and defence." In the 2023–24 Eredivisie, Wieffer ranked highly for blocks, interceptions, ball recoveries and tackles. He was compared to Moisés Caicedo and Alexis Mac Allister after his transfer to Brighton & Hove Albion.

Since April of Brighton's 2024–25 Premier League campaign, Wieffer has been most frequently deployed as a right-back by head coach Fabian Hürzeler, a position he quickly grew accustomed to as he ranks in the 95th percentile of right-backs for tackles won and clearances during the 2025–26 Premier League.

Career statistics Club

International

Netherlands score listed first, score column indicates score after each Wieffer goal KNVB Cup: 2023–24

Individual Feyenoord Player of the Month: January 2023, February 2024