Jetstar is launching a direct Auckland-to-Adelaide service from the middle of December, taking on Air New Zealand with special launch fares of $99 one-way.
Jetstar will fly the route three times a week from December 16, operating every Monday, Wednesday and Saturday.
Adelaide will be the airline's fourth transtasman destination in addition to services to Sydney, Melbourne and Gold Coast from Auckland, Christchurch and Queenstown.
Jetstar's head of New Zealand, Grant Kerr, said the customer response to transtasman flying had been strong over the past few years.
"We know Kiwis love to holiday in Australia and now they can discover or revisit another destination more affordably than in the past."
Fares for Auckland-Adelaide flights will start from $219 one-way online without checked baggage.
Air New Zealand flies daily services to Adelaide from Auckland and special one-way fares start at $250 without bags, according to Air New Zealand's website.
Air New Zealand will also face competition on its Auckland-Perth route over summer from Jetstar's parent company, Qantas.
Jetstar will use an Airbus A320 for the Auckland-Adelaide service, a flight of just under five hours.