On January 5, 2011, Yasin Oztekin signed a deal with Gençlerbirliği for 21 years on a free transfer. On January 12, 2011, he played his first game in the campaign’s against Bucaspor and January 16, 2011, he scored an own goal in the campaign’s against Yeni Malatyaspor. Yasin played 50 games in 1.5 years and scored 8 league goals, which later attracted bigger clubs to target Yasin in the transfer market.

On May 22, 2012, Yasin Oztekin had signed a 4-year deal with Trabzonspor on a free transfer. While playing for Trabzonspor he played 23 games and scored only 3 goals during 2012–2013 Turkish Super League season.

On July 22, 2013, Yasin Oztekin was sent to Kayseri Erciyesspor for a fee of 417 Euros and signed a contract for 3 years. During that season Yasin had played 28 league matches and was able to score 6 goals.

On August 8, 2014, Yasin Oztekin was sold to the Turkish giants Galatasaray for a fee of 2.5 million Euros and signed a contract for 4 years. On February 21, 2015, Yasin scored a fantastic goal in the 9th minute against Sivasspor. On April 5, 2015, Yasin Scored his second goal of the season against Kardemir Karabükspor. On May 12, 2015, Yasin scored an incredible goal in the 16th minute winning over Mersin İdman Yurdu. On May 24, 2015, Yasin scored a critical goal in the 11th minute against Beşiktaş, which led to the win over Besiktas and won the 2014–2015 Turkish Super League.

On June 8, 2015, he made his international debut for Turkey in a 4-0 home friendly win against Bulgaria. He played the first half before being substituted for his club teammate Selçuk İnan.