[11] Güler made his senior debut as a substitute player against Finnish club HJK in the play-off round encounter of the 2021–22 UEFA Europa League.

[12] In his first Süper Lig match three days later, he provided the assist that let Miha Zajc score the winning goal at the 89th minute of the 2–0 victory over Antalyaspor.

After an impressing start to his career, it was reported that big European clubs like Arsenal, Liverpool, Bayern Munich, Borussia Dortmund, Barcelona and Paris Saint-Germain showed their interest in signing him.

[18] On 3 November 2022, he scored his first goal in European competitions, and also provided an assist, in a 2–0 away win over Dynamo Kyiv in the Europa League group stage.

[19] On 11 June 2023, Güler put in a man of the match performance in a 2–0 win at 2023 Turkish Cup final against İstanbul Başakşehir.

[21] On 6 July 2023, La Liga club Real Madrid announced the signing of Güler to a six-year contract lasting until June 2029.

[26] Following multiple injuries in late 2023, Güler debuted for Real Madrid in the Copa del Rey match against Arandina on 6 January 2024,[27] contributing to the team's 3–1 win.

[30][31] Güler made his La Liga debut against Las Palmas on 27 January, coming on as a substitute in the 81st minute, replacing Rodrygo.

[43] With his goal, he also became the fifth-youngest goalscorer in the tournament's history and the youngest debutant to find the net, aged 19 years and 114 days, breaking Cristiano Ronaldo's previous record.