Born in
Sion,
Valais, Quennoz played his youth football and started his career at local club
FC Sion. He advanced to Sion's first team in 1996 under head-coach
Alberto Bigon and during his first season he had five appearances for them, as they topped the table to become Swiss champions. During the next season Quennoz advanced to become a regular starter under new head-coach
Jean-Claude Richard. Quennoz played three seasons for Sion before he moved on. Quennoz joined
FC Basel's first team for their
1999–2000 season under new head-coach
Christian Gross. After playing in four test matches and four games in the
UI Cup Quennoz played his domestic league debut for his new club in the away game on 31 October 1999 as Basel played a 2–2 draw with
SR Delémont. In his first season with Basel Quennoz played in just eight league matches, but then he advanced to become a regular starter. In their
FC Basel's 2001–02 season Quennoz was first choice right back and won the double (league and cup) with the club and advanced to the final of the
UI Cup, but here they suffered defeat,
Aston Villa won 5–2 on aggregate. The following season Basel were runners-up in the league, but they were able to repeat the cup victory as Basel beat
Xamax 6–0 in the final. Quennoz scored his first goal for his club on 19 October 2003 in the
Swiss Cup away game as Basel won 4–1 against
Urania Genève Sport. In their
2003–04 season and
2004–05 season Quennoz and Basel were able to win the domestic league championship another two times. Quennoz played for Basel for seven season, but during the last two he was no longer regular player and therefore he decided to move on. Between the years 1999 and 2006 Quennoz played a total of 243 games for Basel scoring a total of three goals. 98 of these games were in the
Nationalliga A, 14 in the
Swiss Cup, 10 in the
Champions League, nine in the
UEFA Cup, 11 in the
UI Cup and 101 were friendly games. He did not score a goal in the domestic league, but one in cup and the other two were scored during the test games. In 2006 Quennoz joined
Neuchâtel Xamax on a free transfer in search of first-team football. Xamax had just suffered relegation and were strengthening their squad in an attempt to regain promotion to the top flight. This attempt was achieved, as division champions Quennoz and Xamax won promotion. Quennoz played for Xamax for three years. His last game before retirement was in the 3–1 home win on 24 May 2009 against
FC Aarau. Quennoz played nine games for the
Swiss national U-21 football team. ==Private life==