The 2008–09 KFC Twenty20 Big Bash was the 4th season of the official Twenty20 domestic cricket competition in Australia.
Six teams representing six states in Australia participated in the competition.
The competition began on 26 December 2008 when the Queensland Bulls took on the New South Wales Blues at the Brisbane Cricket Ground (Gabba).
Teams received 2 points for a win, 1 for a tie or no result, and 0 for a loss.
In the event of several teams finishing with the same number of points, standings were determined by most wins, then most wins among the teams concerned, then net run rate (NRR).