Didier Deschamps' men meet Finland in their last Group I qualifier on Tuesday, and they should head into that game with a great deal of confidence after producing an excellent performance.
Arsenal striker Giroud was at the heart of a fine display, scoring twice in the first half after Bayern Munich star Franck Ribery had opened the scoring with a penalty.
Further strikes from Newcastle United duo Yohan Cabaye and Mathieu Debuchy added to Australia's misery, before Real Madrid forward Karim Benzema ended a 16-month goal drought to put further gloss on a superb showing.
Newcastle striker Loic Remy made his first appearance for France since March as he was named in the starting XI, while Australia's side featured six changes from their 6-0 defeat to Brazil last month.
The hosts continued to dictate in the early stages, and they soon doubled their advantage, Giroud latching on to Ribery's pull back before lifting a sublime finish over Langerak and into the bottom corner.
France continued to surge forward and duly added a fourth on the half-hour mark through Cabaye, who lashed a powerful finish into the bottom corner from the edge of the area after meeting Ribery's lay-off.
France refused to relent and dished out further punishment shortly after, substitute Benzema turning home Ribery's left-wing cross to score his first goal for the national team since June 2012.
Tim Cahill created Australia's only chance as he curled over from distance, while Remy, Nasri and substitute Moussa Sissoko all went close at the other end, but it mattered not as France coasted to an easy win.
