Mr Fischer said Pope Francis was on the radar screen some years ago but he was dismissed as too old, with another Argentinian cardinal tipped as more likely.
"Pope Francis I will bring about change. You can be sure of that. A Latin American pontiff, someone a long way from Rome and a Jesuit to boot - that spells conservative approach maybe but change and change where it's needed on the financial administration of the Vatican and the clergy sex abuse issue and others," he told ABC television.
Mr Fischer, who was deputy prime minister under John Howard, said the next important step would be to see who he appointed as secretary of state, effectively the prime minister of the Holy See.
He said this was the first pope from the southern hemisphere.
"Certain elements of the curia who need to be moved on and moved along will not necessarily be that happy this particular night in Rome," he said.
Mr Fischer said Pope Francis was a humble man who knew what it was like to be poor.
"The key is, can this new Pope Francis I communicate and can he communicate in Spanish - obviously yes - in Italian - obviously yes - in English, we shall see," he said.