in 1971 he joined stade de reims at the same time as his compatriot zywica, finishing his first season with 22 goals and his second season with 17. in 1974 the newly promoted as monaco signed him and over the next 7 seasons he was their top scorer every year, eventually scoring 223 goals, with 157 in the league. in 1976 the club were relegated, but onnis stayed with them and helped them regain their top flight status for the 1977-78 season that saw them finish as league champions, and the following season win the coupe de france.