"We wouldn't be making any money without transformation," said chief executive Alan Joyce.
Unit costs dropped 4.8 per cent and revenue increased by 2.1 per cent to A$8.1 billion.
While lower fuel costs contributed about A$33 million to the improved performance in the first half, one analyst says it could save up to A$500 million for the remainder of the financial year.
The underlying profit result is Qantas' best since the first-half performance in 2010 but it will not pay a dividend and intends paying back A$1 billion of debt.
The group's statutory profit after-tax of A$203 million is a massive turnaround on a statutory loss of A$235 million a year ago.
See Air NZ video: Cheaper fares could be coming
Qantas International was profitable for the first time since the global financial crisis, with underlying earnings of A$59 million representing a turnaround of A$321 million.
Increased fleet utilisation enabled the international arm to add capacity to destinations including Los Angeles, Dallas/Fort Worth, Vancouver, Santiago, Honolulu and Auckland. Capacity will grow across the network by up to 2 per cent this year, including some extra seasonal flying to New Zealand.
In the domestic market, Qantas and Jetstar reported combined pre-tax earnings of close to A$300 million as the capacity war with Virgin Australia abated.
The resurgence of Qantas is providing more intense competition for Air New Zealand on routes where they compete and will be a factor in more discounted air fares in the coming year.
Qantas shares closed up 4c yesterday at A$2.85.
Australia cuts back promotion
Tourism Australia is scaling back on brand promotion in New Zealand because Kiwis have got the message and they don't spend as much as other visitors. The Australian Government and private sector-funded organisation has cut its Auckland office from about five staff to one as it redirects marketing of Australia around the world. The organisation is chasing value, rather than volume.