For the 2008–09 season, Adelaide United made some significant signings to strengthen the squad, most notably striker Cristiano from Willem II for two years on a free transfer.

Bobby Petta, Shaun Ontong, Milan Susak, Dez Giraldi and Robert Bajic were all released, Bruce Djite was sold for an A-League record of A$850,000 to Genclerbirligi, whilst Nathan Burns also transferred to pursue his European dreams, joining Greek first division outfit AEK Athens[1] for A$500,000.

This season, Adelaide United passed the one millionth spectator milestone of total crowds since the inception of the A-League.

An early highlight for the season was Adelaide's run to the final of the AFC Champions League against Gamba Osaka.

[7][8] The Reds' next game was played against AFC Champions League rivals, Gamba Osaka, in the quarterfinal round on 14 December in Toyota, Japan.

Former Adelaide player Richie Alagich, along with Michael Barnett and former Socceroos Tony Vidmar and Joe Mullen joined the coaching staff of these teams.