Australian Transport minister Warren Truss said the new search area was based on fresh analysis of existing satellite data from Malaysia Airlines Flight 370.
The plane vanished during a flight from Kuala Lumpur to Beijing on March 8 with 239 passengers and crew aboard.
The shift was expected. The head of the Australian Transport Safety Bureau said last week it would move south of an area where a remote-controlled underwater drone spent weeks fruitlessly scouring 330 square miles of seabed.
Martin Dolan, chief commissioner of the Australian Transport Safety Bureau, said "certainly for its path across the Indian Ocean, we are confident the aircraft was operating on autopilot until it ran out of fuel".
Mr Truss said officials have not attempted to fix the time when the plane was put on autopilot.