2005–06 Adelaide United FC season

The 2005–06 Adelaide United FC season was the club's second season since its establishment in 2003. The club participated in the A-League for the first time after the National Soccer League was replaced.

Continuing their good form from the final season of the NSL, Adelaide United finished as Premiers in the inaugural season of the Hyundai A-League.

The Reds were bundled out of the finals race in straight sets losing to Sydney FC in the two leg semi final and then Central Coast Mariners 1–0 in the preliminary final at Hindmarsh.