Bulgurlu looked after Belözoğlu for four years, teaching him all the basic techniques, improving and harnessing his fitness and stamina dramatically.

[5] In the 2002–03 season, Belözoğlu became the 17th winner of the Pirata d'Oro (Golden Pirate), an annual award given for the Inter Milan best player of the year.

In his fourth game on 23 October, he set up the opening goal with a corner to Shola Ameobi, and later scored the winner with a free kick, in a 3–2 victory over Sunderland in the Tyne-Wear derby.

[6] Of 25 games in all competitions in his first season, 20 in the league, he scored just one more goal: a long range shot on 5 November to defeat Birmingham City 1–0.

However, Belözoğlu stated that he had always been a Fenerbahçe fan, which has been confirmed by some of his past team-mates, including Galatasaray legends Hakan Şükür and Hasan Şaş.

He was effective at both ends of the pitch, his experience and combative style proving a valuable asset in taking his team so close in both league and cup.

On 3 November 2010, Belözoğlu declared that he hung posters of former Fenerbahçe players Aykut Kocaman, Rıdvan Dilmen and Džoni Novak on his walls at home.

[12] On 7 July Belözoğlu trained with his new teammates before being unveiled by Atlético in a signing ceremony held in the Vicente Calderon stadium.

He made his Atlético debut on 1 September 2012 in the UEFA Super Cup against Chelsea, coming on for the last three minutes in place of Radamel Falcao whose hat-trick contributed to Atletico's 4–1 victory.

On 7 July 2020, in the 31st week of the league, he scored a goal in the 81st minute against Gençlerbirliği, securing a 1–1 draw and earning Fenerbahçe 1 point.

Injury forced him out of the Euro 2000 but he was part of the Turkish squad that finished in third place at the 2002 FIFA World Cup.

Belözoğlu played the opening match of UEFA Euro 2008, but an injury sidelined him for the rest of the tournament as Turkey progressed to the semi-finals.

[23] On 4 October 2021, Belözoğlu signed a two-year contract to manage İstanbul Başakşehir, returning to the team he had captained for four years.

[31][32] Belözoğlu's transfer from Inter Milan to Newcastle United in July 2005 is one of those about which the Stevens inquiry report in June 2007 expressed concerns.

[33] Belözoğlu was accused of using racist insults towards Everton's Joseph Yobo, Tim Howard and Joleon Lescott during a match on 30 December 2006.

He denied these claims, and he was charged by The Football Association in January 2007 and found not guilty by an independent commission in March.

[34] In February 2007, the FA announced another investigation into alleged racist remarks from Belözoğlu, this time aimed against Bolton Wanderers striker El-Hadji Diouf in a 2–1 win at St James' Park on 15 October 2006.

[41] According to Sait Aksoy, who is known as the 'football imam' of FETÖ, Belözoğlu, who allegedly attended chats organised by the Gülen movement during his football career, was told by coach Fatih Terim: "Stop your relationship with Fethullahists.

However, later on, a decision of non-prosecution was issued on the grounds that attending a chat and giving money was not sufficient evidence for membership of the organisation.