The 2005 AFL season was the 109th season of the Australian Football League (AFL), the highest level senior Australian rules football competition in Australia, which was known as the Victorian Football League until 1989. The season featured sixteen clubs, ran from 24 March until 24 September, and comprised a 22-game home-and-away season followed by a finals series featuring the top eight clubs.

The premiership was won by the Sydney Swans for the fourth time, after they defeated West Coast by four points in the AFL Grand Final. It was the club's first premiership since it won the 1933 premiership as South Melbourne, and ended a 72-year premiership drought which stands as the longest in league history.

Carlton defeated West Coast 1.14.18 (111) to 1.11.9 (84) in the Grand Final.

• The Brownlow Medal was awarded to Ben Cousins of West Coast. Ben Cousins received 20^[6] votes to beat fellow West Coast midfielder Daniel Kerr.
• The Leigh Matthews Trophy was awarded to Ben Cousins of West Coast.
• The Coleman Medal was awarded to Fraser Gehrig of St Kilda.
• The Norm Smith Medal was awarded to Chris Judd of West Coast.
• The AFL Rising Star award was awarded to Brett Deledio of Richmond.
• The Wooden Spoon was "awarded" to Carlton for coming last. They became the first team in AFL history to win the pre-season competition and then finish last in the season proper.

• 30 players retired from the game, including Matthew Primus, Nick Holland, Martin Pike, Wayne Campbell, Justin Murphy, Brenton Sanderson, Austinn Jones, Angelo Lekkas, Phil Matera, Jason Ball and Stuart Maxfield. Shane Woewodin, a Brownlow Medallist, was delisted.^[7]

• Essendon coach Kevin Sheedy coached the Australians to a 2–0 victory in the 2005 International Rules Series against Ireland. Andrew McLeod won the Jim Stynes Medal.
• Fremantle defeated West Coast by 17 points in an exhibition match played in London.
• Sydney and the Kangaroos played an exhibition match in the United States at UCLA, with the Kangaroos winning by 48 points.

Three players celebrated 200th game milestones against eventual premiers the Sydney Swans during the regular season:

• Fraser Gehrig (St Kilda), round 10^[8]
• Jeff White (Melbourne), round 16^[9]
• Scott Lucas (Essendon), round 19^[10]

Additionally, Michael Voss (Brisbane Lions) played his 250th AFL game and Mal Michael his 100th club game for the Lions, both also against the Swans, in round 3.^[11]

The Swans won the premiership despite being ranked 14th in scoring during the regular season, their 1,974 points scored for being 42 points less than wooden-spooners Carlton which scored 2,016 points from their twenty-two matches.^[12]