Jetstar will fly from Christchurch to Melbourne every day all year long, with 26,000 additional seats on that route.
And the Auckland-Dunedin service will increase from seven flights a week to 10 a week from October 26 to May 17, with 24,000 additional seats a year.
Jetstar will base another Airbus A320 in Auckland.
The airline said it had re-timed its Auckland-Wellington flights to a 7.30am departure to give business and Government travellers more convenience and choice.
Jetstar said the expansion would also cater for New Zealanders travelling to Asia using Australia as a springboard.
“Double daily services from Auckland to Brisbane will allow customers to connect to Osaka, Tokyo, Seoul, Bangkok, Phuket and Cebu, with one short stop in Brisbane.”
It said more Christchurch-Melbourne flights would allow Kiwis to head from Melbourne to Singapore, Bangkok, Bali, Phuket and Ho Chi Minh City.
“The carrier has also brought forward departure of its Christchurch to Cairns flights to 7am to allow for connections via North Queensland on to Tokyo.”
Jetstar group chief executive Stephanie Tully said the expansion would boost Jetstar’s NZ domestic capacity by 18% and by 14% across the Tasman.
“These changes will give a much-needed boost to inbound tourism while offering Kiwis even more low fares and choice in how they travel,” Tully said.