*Club domestic league appearances and goals, correct as of 21:15, 20 December 2024 (UTC) ‡ National team caps and goals, correct as of 20:00, 12 September 2023 (UTC)
Ünder began his professional career at Altinordu, and later transferred to Başakşehir.[3] In his breakout season with Başakşehir, Ünder established himself as one of the best players in the league, scoring 7 goals in 32 games in his debut season in the Süper Lig.[4]
Roma
On 16 July 2017, he became a Roma player for a €13.4 million fee.[5] He scored his first goal for Roma in a 1–0 win over Hellas Verona in the Serie A on 4 February 2018.[6] In the same month, he marked his Champions League debut with a goal; the opener in a 1–2 loss to Shakhtar Donetsk in the first leg of the first round of knockout fixtures,[7] becoming the youngest Turkish player ever to score in the Champions League.[8]
Leicester City (loan)
On 20 September 2020, Ünder signed for Premier League club Leicester City on a season-long loan, with the option of a permanent transfer.[9] He made his debut in a 3–0 defeat to West Ham United, coming on as a substitute.[10] On 25 October, he made his first goal contribution for Leicester when he assisted Jamie Vardy's winning goal in a 1–0 away win over Arsenal, which ended Leicester's 47-year wait for a victory away at Arsenal.[11] On 10 December, Ünder scored his first Leicester goal in a 2–0 home win over AEK Athens in the UEFA Europa League.[12]
Marseille
On 4 July 2021, he signed on loan for Ligue 1 club Marseille, with an option to be bought[13] of €9 million.[14] On 8 August 2021, he made his debut with the team against Montpellier in Ligue 1, Marseille won 3–2.
On April 6, 2022, Marseille used the option and signed permanent 5 years contract.[15]
Fenerbahçe
On 13 August 2023, Ünder signed a four-year contract with Süper Lig club Fenerbahçe for a reported fee of €15 million.[16][17] On 21 August 2023, he made his debut with the team against Samsunspor in Süper Lig away game, Fenerbahçe won 2–0.[18]
On 20 December 2023, he scored his first goal for the team against Kayserispor in league match that Fenerbahçe won 4–3. On 7 January 2024, after a slow start to his career with Fenerbahçe, he scored four goals in a 5–1 win over Istanbulspor.[19]
In November 2016 Ünder received his first call-up to the senior Turkey squad for the match against Kosovo.[21] He scored his first international goal in his second cap for his country in a friendly victory against Moldova in March 2017.