Mert Muldur (born 3 April 1999) is a professional footballer who plays as a right back or a centre back for Super Lig club Fenerbahce. Born in Austria, he represents the Turkey national team. Mainly a right-back, Muldur is a versatile defender capable of playing in multiple positions.

Muldur joined the SK Rapid Wien youth academy at the age of six in 2006, and worked his way up into the professional team. Muldur made his professional debut for SK Rapid in a 4–1 Austrian Football Bundesliga loss to FC Red Bull Salzburg on 13 May 2018. On 29 May 2018, Muldur signed his first professional contract for three years with Rapid Wien.

On 20 August 2019, Muldur signed with the Italian club U.S. Sassuolo Calcio. He made his debut five days later, coming on as a substitute in 2–1 away loss against Torino.

On 15 August 2022, he suffered an ankle fracture injury in season start match against Juventus and missed 16 matches.

On 2 August 2023, Fenerbahce announced Muldur signed a four-year contract with Fenerbahce until 2027.

He made his debut with the team in a 3-0 UEFA Europa Conference League win over NK Maribor on 17 August 2023. On 21 August 2023, he made his Super Lig debut with the team against Samsunspor in away game, Fenerbahce won 2–0.

Born in Austria to Turkish parents, Muldur is a youth international for Turkey. Muldur made his debut for the senior Turkey national team on 11 October 2018, in a 0–0 friendly against Bosnia and Herzegovina.