Yannis Tafer was born on 11 February, 1991 in the city of Grenoble in the Rhône-Alpes region to an Algerian father, who emigrated to France from Constantine, and a Portuguese mother. He is an Algerian footballer who plays for Swiss club FC St. Gallen in the Swiss Super League. Yannis is the cousin of Aziz Tafer, who plays for French side Grenoble Foot 38. Tafar cites his idols as former teammate and mentor Karim Benzema and former Brazilian international Ronaldo. He is a France youth international having represented the country under-17, under-18, and under-19 level.
Tafer was the top scorer at the 2008 UEFA European Under-17 Football Championship leading the tournament with four goals and played on the under-19 team that won the 2010 UEFA European Under-19 Football Championship. He began his football career with a local club in the region, FC Échirolles. After spending seven years with his childhood club, Tafer signed an aspirant (youth) contract with the then three-time champions Olympique Lyonnais.
Following the 2007–08 season, Yannis signed his first professional contract with Lyon agreeing to a three-year contract until 2011. For the 2008–09 season, he was placed on Lyon’s first-team squad and was assigned the 34 shirt, though he was reassigned to the number 29. Tafer was a key participant in the club’s preseason tour playing in four of the five matches contested.
On 24 August 2010, Lyon confirmed that the club had loaned out Tafer to fellow Ligue 1 club Toulouse. The loan was for the entire 2010–11 season and had a buyout option for €4 million, On 25 July 2012, following his release from Lyon, Tafer signed a three years contract with Swiss club Lausanne-Sport, On 5 June 2014, Tafer moved to St. Gallen signing a three-year contract until 2017.
Yannis is a France youth international having played under-17, under-18, and under-19 level. He made his youth international debut with the under-17 team on 2 October 2007 against Switzerland. Tafer scored a brace in the team’s 4–0 victory. On 4 December 2007, he scored both goals in the team’s 2–1 win over Turkey.