His impressive European performance with Denizlispor led him to Fenerbahçe, where he faced challenges and triumphs, including winning the Super Lig and earning a spot in Turkey national football team.
He was signed by Rıza Çalımbay for Denizlispor at the start of the 2002–03 season in a deal which also involved Ersen Martin and Mustafa Özkan.
With interest in Çetin high by the big clubs in Turkey, Denizlispor reached an agreement with Fenerbahçe for a reported $1.5 million for the strong centre back to start the 2003–04 season.
After the sacking of Christoph Daum at the end of the 2005–06 season, his replacement Zico signed the central defender pairing of Diego Lugano and Edu Dracena.
[5] After settling into the team and under the tutelage of Karl-Heinz Feldkamp, Çetin's play improved immensely and he managed to become a favourite of Galatasaray fans shortly thereafter.
Çetin made almost 50 appearances and chipped in with five goals in the league winning campaign and became a fixture in the Turkey National Team.
On 26 November 2012, Çetin showcased a memorable performance when Eskişehirspor defeated Trabzonspor 3–0 at Hüseyin Avni Aker Stadium.
During this match, Servet initiated a play from the defense, carrying the ball from the center of Trabzonspor's half, eluding opponents with dribbles and a body feint.
Primarily partnering with Diego Ângelo in central defense, Servet concluded the season with 26 league appearances and 2 goals.
Despite contemplating transfers to Çaykur Rizespor and Elazığspor, he ultimately remained with the team due to Jerry Akaminko's injury and regained his position, including Turkish Cup matches.
During his time in goal, he made numerous crucial saves and prevented the opposing team from scoring, including stopping a penalty taken by Taye Taiwo after a foul by Dedê in the 83rd minute.
Despite his efforts, Çetin couldn't prevent Stanislav Šesták's goal in the 90+4 minute, and the match concluded with a 3–1 victory for Bursaspor.
Eventually, he signed a 1-year contract with Mersin İdman Yurdu, a team managed by Rıza Çalımbay, who also brought in players like Serkan Balcı, Márkó Futács, and Welliton.
He made his debut for Turkey in a 0–4 friendly match loss against Czech Republic on 30 April 2003,[6] coming on for Alpay Özalan in the 83rd minute.
This transition showcased his evolution from a player to a coach, and his new role presented opportunities to apply his football knowledge and leadership skills.
In UEFA Euro 2008 Çetin's injuries included a torn groin, strained knee ligaments, a broken tooth and a bruised hip bone all at once.