Mathias Jensen (born 1 January 1996) is a Danish professional footballer who plays as a central midfielder for Premier League club Brentford and the Denmark national team.

Jensen is a product of the Nordsjælland academy and began his senior career with the club in 2016. Following two seasons as a regular member of the team, he transferred to Celta Vigo in 2018. After an injury-hit 2018–19 season, he transferred to Brentford and was a part of the squad which was promoted to the Premier League in 2021. A former Denmark youth international, Jensen made his full international debut in 2020. He was a member of the Denmark squads at Euro 2020, the 2022 World Cup and Euro 2024.

A midfielder, Jensen progressed through the academy at Nordsjælland and signed a three-year professional contract in January 2015. He was promoted into the first team squad for the 2015–16 season and made five appearances during the campaign, scoring one goal, which came in a 2–2 draw with Randers on 1 May 2016. Jensen was a regular in the 2016–17 season, making 22 appearances, before 2017–18 proved to be his breakthrough season.

He made 36 appearances, scored 12 goals, was awarded the captaincy and his achievements were recognised by the DBU and his club, with the DBU 2017 Talent of the Year and FC Nordsjælland Player of the Year awards respectively. After three early 2018–19-season appearances, Jensen departed Nordsjælland in August 2018. During just over three seasons as a professional at Farum Park, Jensen made 66 appearances and scored 15 goals.

On 8 August 2018, Jensen moved to Spain joining La Liga club Celta Vigo on a five-year contract. During an injury-affected 2018–19 season, he made just six appearances and left the club in July 2019.

On 10 July 2019, Jensen moved to England signing with Championship club Brentford on a four-year contract, with the option of an additional year, for an undisclosed fee, reported to be £3.5 million. He made 43 appearances and scored one goal during the 2019–20 season, which ended with defeat in the 2020 Championship play-off final. Jensen made a career high 53 appearances during the 2020–21 season and celebrated promotion to the Premier League with victory in the 2021 Championship play-off final.

As a result of suffering a "badly gashed" foot while away on international duty, Jensen missed Brentford's entire 2021–22 pre-season and the first three matches of the regular season. Restricted to a mix of starting and substitute roles, particularly after the January 2022 signing of Christian Eriksen, Jensen made 35 appearances during a "stop-start" season. Despite being affected by COVID-19 and another minor injury, Jensen won praise from head coach Thomas Frank for training "like an animal" while sidelined.

Entering the final year of his contract, Jensen hired his own personal trainer to work with him daily during the off-season in Denmark and he returned for the 2022–23 pre-season "in incredible shape". He was challenged by head coach Thomas Frank to be the replacement for the departed Christian Eriksen. Jensen began the regular season in a starting role and as a regular set piece taker. Coaching from specialist throw-in coach Thomas Gronnemark helped length his throws. Jensen's performance and first Premier League goal in a 4–0 win over Manchester United on 13 August 2022 was recognised with the man of the match award.