Şahin was born in Tarsus, Mersin. He began his footballing career as an 11-year-old with Yeşilova Yeni Ufukspor. He was transferred to Sefaköy Özmuratspor in 1999, and earned a transfer to Samsunspor in 2004. After spending a season playing for the A2 team, where he scored 11 goals in 26 matches, Şahin was signed to a five-year professional contract. He made his debut as a substitute on 9 December 2006, coming on for Mustafa Çiçek in a match against Gaziantep Büyükşehir Belediyespor. Şahin played a total two matches that season. He did not receive many chances at the beginning of the 2007–08 season, but slowly found a place in Orhan Kapucu's team. On 17 February 2008, he scored a goal in the final minutes against Orduspor to help save Samsunspor from defeat. It was his first professional league goal. At the beginning of the 2008–09 season, Şahin was a starter in the Samsunspor side. However, he was unable to score a goal in the first seven matches of the season. Several weeks later, in a match against Gaziantep Büyükşehir Belediyespor, Şahin was involved in a fist fight with Gaziantep B.B. player Hakan Albayrak. Both players received a red card as a result. Four days later, Şahin was given a three match ban by the PFDK for his actions. In his first match back from his ban, Şahin netted a goal against Kartalspor. Şahin received another red card in the 33rd round of the league against Sakaryaspor, resulting in another three match ban for unsportsmanlike conduct. He finished the season with eight goals in 29 matches. Trabzonspor, as well as Ankaraspor, Antalyaspor, Gaziantepspor and Kayserispor showed interest in Şahin and his teammate Sercan Temizyürek before the start of the 2009–10 season, causing the forward to become unsettled. He netted his first goal of the season in the third round against Çaykur Rizespor, having been suspended the first two matches from an outstanding ban. Şahin went on to bag a hat trick against Kayseri Erciyesspor on 21 November 2009. He tallied seven goals by the winter break. Şahin went on to score several more goals, finishing with 15 in 29 matches. At the end of the 2009–10 season, Samsunspor met with three clubs inquiring about Şahin's availability. After several meetings, the club came to terms with MKE Ankaragücü on a $900,000 transfer fee, as well as two players, in exchange for Şahin. Şahin signed a five-year contract with his new club. After battling injuries, he made his debut for the club and scored his first Süper Lig goal in a 4–2 defeat of Galatasaray on 17 October 2010.
