The Expansion of the A-League Men is the ongoing process of establishing new clubs in the A-League Men. The A-League Men was established to replace the National Soccer League as the top division in the Australian football league system. It is the only professional football league in the country. Founded in 2004 with eight teams commencing competition in the 2005–06 season, the league has since expanded into new markets across Australia and New Zealand. From the 2024–25 A-League Men season, 13 clubs will compete in the league, after Auckland Football Club was granted an expansion license.

There is also a long term prospect of teams being added to the A-League Men from a second division that involves Promotion and relegation. Football Australia and the Association of Australian Football Clubs, a group of clubs that currently exist in the state & regional "Member Federations" have been working to implement a second division team with an eventual goal that a football pyramid that would see clubs move between the A-League Men & the second tier, and between the second tier & state leagues.

Football Federation Australia (FFA) exercised caution when forming the A-League Men in early 2004; in terms of selecting who was to be part of the new league. FFA decided upon a 'one city – one team' principle in order to protect the initial development of the foundation clubs.

The initial eight teams selected were Adelaide United, Brisbane Roar (formerly Queensland Roar), Central Coast Mariners, Melbourne Victory, Newcastle Jets, Perth Glory, Sydney and New Zealand Knights. Of these 8 clubs, only the New Zealand Knights have failed to survive, folding after the 2006–07 season.

Before the introduction of the A-League Men, FFA chairman Frank Lowy speculated that he hoped to expand the league into other cities, citing Adelaide, Canberra, Hobart, Wollongong, Coffs Harbour, Geelong, Bendigo, Cairns, Ballarat, Albury-Wodonga, Launceston, Christchurch, Auckland, Sunshine Coast and Darwin.

In late October 2006, as a result of low crowd attendance at North Harbour Stadium in Auckland and continual poor on-field performances, rumours began to circulate that the FFA was considering revoking the A-League licence of the only New Zealand based A-League club, New Zealand Knights, and granting it to a new club that would enter the competition in the 2007–08 season. The FFA had continued to express angst at low attendance numbers, poor on-field performance and the lack of domestically developed players.

On 14 December, the FFA announced that it had revoked the competition licence held by the Knights' owners, and on 19 March 2007 after several delays, Wellington Phoenix was selected as the successor to the New Zealand Knights.

In 2009, the league expanded in Gold Coast with the new club Gold Coast United and in Townsville with the club North Queensland Fury. Expansion into these new regions was seen as critical to the success of the 2022 Australian FIFA World Cup bid. In 2011, after the failed bid, North Queensland Fury was removed from the league due to financial instability. In 2012 Fury re-formed to participate in the National Premier League Queensland. In 2012, the FFA revoked Clive Palmer's Gold Coast United A-League licence.