Adelaide United Football Club is a professional men's soccer club located in Adelaide, South Australia, Australia. The club, nicknamed the Reds, was one of the eight founding members of the A-League Men and have competed in it concurrently since its formation. They currently hold a licence from the Australian Professional Leagues. Established in 2003, the club was formed to replace Adelaide City and West Adelaide in the final season of the National Soccer League, and has remained the only A-League club from South Australia. Adelaide United's home ground is at Coopers Stadium in the inner north-western suburb of Hindmarsh.

A-League Men is the highest-level professional men's soccer league in Australia and New Zealand. At the top of the Australian league system, it is the country's premier men's competition for the sport. A-League Men was established in 2004 as the A-League by the Football Federation Australia (FFA) as a successor to the National Soccer League (NSL) and competition commenced in August 2005. The league is currently administered by the Australian Professional Leagues (APL), contested by twelve teams; eleven based in Australia and one based in New Zealand. The men's, women's and youth leagues have now been brought together under a unified A-Leagues banner.