The ACT and Northern Territory will be guaranteed at least two seats in the House of Representatives under laws set to pass federal parliament by the end of the year.
The Morrison government announced on Friday it had agreed with the finding of a bipartisan inquiry that both territories should get legal protection to ensure their proper representation.
The laws will ensure the NT and ACT have a two-seat minimum representation.
As well the government will consider greater resourcing for members with large electorates.
The NT was expected to lose one of its two seats in a forthcoming redistribution, due to population shifts.
Victoria is set to gain another electorate at the next federal election, rising to 39, while Western Australia will lose one of its 16 seats.
Labor argued the NT would become the most under-represented place in Australia, with just one MP representing 250,000 people and covering 1.4 million square kilometres including the remote Indian Ocean Territories of Christmas Island and the Cocos Islands.