[4] In January 2017, he was loaned out to Sporting B, and made his professional debut in the Segunda Liga for the latter club on 5 February 2017 in a 1–1 home draw against Famalicão.

[15] He subsequently made his Champions League debut on 11 December, in the club's final group match, earning praise in the media for his performance as he helped Juventus keep a clean sheet in a 2–0 away win over Bayer Leverkusen.

[16][17] He scored his first goal for the club on 12 January 2020, the opener in a 2–1 away win over Roma, which saw Juventus secure the unofficial title of "Winter Champions", though he was later substituted for Matthijs de Ligt after sustaining an anterior cruciate ligament injury.

[30] Demiral is usually deployed as a centre-back, in either a three or four-man defence, although he is a versatile player, who is also capable of playing as a right-sided full-back.

[31] An aggressive and instinctive defender, his main traits are his physicality, tactical intelligence, tackling, composure, and determination, which allow to excel at reading plays, and also enable him to anticipate or mark his opponents well.

[31][32] Regarded as a promising young defender in the media, due to his characteristics, he has been compared to Nemanja Vidić, whom Demiral himself has also cited as an inspiration.

[38][39][40][41] On 2 July 2024, after the match against Austria in the Euro 2024 in Germany, Demiral displayed the so-called wolf salute, which is associated with Turkish nationalism, pan-Turkism, and the Grey Wolves organization.

In addition to criticism from politicians and journalists,[44] UEFA started an investigation for alleged inappropriate behaviour.

[49] UEFA's ban on Demiral was criticised by some as hypocritical and of double standard by drawing comparisons with the lighter penalty received by Jude Bellingham for offensive gesture made at the same tournament and with political gestures made by footballers of other nations which had gone unpunished in previous editions of the tournament.