Cyclone Debbie caused major damage, torrential rain and power cuts to tens of thousands of homes.
Defence force helicopters and naval vessels carrying aid are to be despatched to Queensland.
Mr Turnbull said one death had been confirmed but added that emergency crews had yet to assess the damage.
Cyclone Debbie made landfall between Bowen and Airlie Beach as a category four storm, whipping gusts of up to 263km/h (163mph).
It is moving inland as a category two storm but could cause more damage.
