Güvenışık began his career in the youth setup of VSC 1862 Donauwörth. In 1997, he joined the youth program of FC Augsburg. After a brief stint in the youth system of FC Bayern Munich he returned to Augsburg and played for the club in the Regional league, scoring 10 goals in 29 appearances. In 1999, he signed for Bundesliga side MSV Duisburg and made his debut in the top flight at 19 years of age. In four years with the club Güvenışık made 80 league appearances and scored 12 goals. In July 2003, he joined Turkish First Division side Denizlisporon loan, but left after only six months to join the Southern Regional League club 1. SC Feucht. The following season he returned to Turkey signing with Turkish First Division side Manisapor. Due to payment irregularities he returned to Germany after only six months. He joined SC Preußen Münster for the second half of the North Regional League and went on to score six goals in 11 games, becoming a crowd favorite, but could not prevent the club's relegation. In the summer of 2006, he joined 2. Bundesliga club FC Carl Zeiss Jena but was unable to make an impact for the side as he was sidelined for six months due to a cruciate ligament injury. In June 2007, he signed for Rot-Weiss Essen on a one-year contract. He appeared in 24 league matches for the club and scored six goals. For the 2008–09 season, Güvenışık moved to third division side SC Paderborn 07. In his first year at the club, Güvenışık scored 17 goals in 30 matches as he helped lead Paderborn 07 to promotion to the second division. The following season, he only made nine appearances for the club and during the winter break returned to SC Preußen Münster. Upon his return, he continued to be a crowd favorite and during the 2010–11 season helped the club gain promotion to the third division by scoring seven goals in 25 matches. In his second spell with the club, Güvenışık appeared in 56 league matches and scored fourteen goals. Güvenışık signed with Major League Soccer club San Jose Earthquakes on 26 January 2012. San Jose released him after the 2012 season and he trialed with Columbus Crew SC during the 2013 preseason, but was not offered a contract.
International career
Güvenışık represented Turkey at the Under 17 and the Under 21 levels.
