The 2009 Australian motorcycle Grand Prix was the fifteenth round of the 2009 Grand Prix motorcycle racing season. It took place on the weekend of 16–18 October 2009 at the Phillip Island Grand Prix Circuit. Ducati rider Casey Stoner won the grand prix, in his home race. Championship leader Valentino Rossi finished second, further increasing his championship lead over rival Jorge Lorenzo, who crashed out and failed to score any points. This also marked the final Grand Prix win in the career of Marco Simoncelli before his death 2 years later on 23 October 2011 at the 2011 Malaysian motorcycle Grand Prix after suffering a fatal crash in Race.

The 2009 Grand Prix motorcycle racing season was the 61st F.I.M. Road Racing World Championship season. The season consisted out of 17 races for the MotoGP class and 16 for the 125cc and 250cc classes, beginning with the Qatar motorcycle Grand Prix on 12 April 2009 and ending with the Valencian Community motorcycle Grand Prix on 8 November.