Depending on sources, it is agreed that Ajaccio began playing in 1909–10. Their adopted colours are red and white stripes. Though they used to play in what was previously utilised as a sand dump, they decided to move to another, cleaner, safer stadium upon the insistence of Jean Lluis, father-in-law of club president Louis Baretti. The new stadium that was chosen held 5,000 spectators and was in use until 1969.
AC Ajaccio were elected Corsican champions on eight occasions, in 1920, 1921, 1934, 1939, 1948, 1950, 1955 and 1964, and are one of three big "island" teams, along with Gazélec Ajaccio and SC Bastia, the competition between the three being kept no secret. Spectators during the 1946 Corsican Cup final, held between A.C.A. and Sporting Bastia were handed umbrellas to shield themselves from the violence. Upon refusal of a penalty which would have been awarded to ACA, violence erupted between the fans, who used umbrellas both as cause and limitation of violence. This final was abandoned and replayed much later.
A.C.A. became a professional team in 1965 thanks to the ambitious assembly of a team by leaders of the club. They initially adopted the symbol of the polar bear, but this has since been dropped in favour of a more stylised logo that uses a part of the Corsican flag.