Ambroise Oyongo began his career with Moussango FC of Yaoundé in 2008. His play with Moussango attracted the interest of top club Coton Sport FC who signed Oyongo in July 2010. Oyongo quickly established himself at the club winning the league title in his first year with Coton Sport. In 2011 he helped the club to the league and cup double. In 2013 he won another league title and helped lead Coton Sport to the semi-finals of the 2013 CAF Champions League.
During the 2013 season Oyongo went on trial with French side Lille and it was reported that he would be joining the Ligue 1 side during the 2014 January transfer window. The move never materialized and in January 2014 Oyongo went on trial with New York Red Bulls. Oyongo impressed during his trial and on March 7, 2014 he officially signed with the club.  In his first season with New York the versatile Oyongo was a key player for the club during the second half of the season as he made starts at both left back and in midfield helping his side qualify for the league playoffs. On October 30, 2014 Oyongo assisted on Bradley Wright-Phillips winning goal in the last minute of the match helping New York defeat Sporting Kansas City and advance to the Eastern Conference Semifinals. On January 27, 2015 he was traded to the Montreal Impact for Felipe Martins.