Jetstar is adding an extra 15,000 extra seats between Australia and Queenstown in July and August using 180-seat A320s.
Grant Kerr, head of Jetstar New Zealand, said Melbourne-Queenstown services would rise from four times a week to daily and Sydney-Queenstown from three to five per week.
Qantas will step up to daily flights from Sydney between July and October.
Scott Paterson, Queenstown Airport Corporation chief executive, said pressure on the arrivals area at the height of the ski season meant the company was putting up a heated marquee to house a second baggage claim area.
Destination Queenstown chief executive Graham Budd said the airlines' additional capacity was significantly up on the usual winter boost.
Although there would be pressure on accommodation at peak times, "it's a good problem to have".
Latest figures from Queenstown Airport show that in the financial year to date the number of international passenger movements has grown 28 per cent to more than 225,000.