Canberrans will vote in three lower house seats at the next federal election, with a territory-wide redistribution process to be put in motion on Friday.
The Australian Electoral Commission confirmed the new seat would be created on the back of nation-leading population growth figures released in June, coming as the House of Representatives grows by one seat to 151 members from the next poll.
Victoria will add one new federal electorate, to have 38 seats and South Australia will drop from 11 seats to 10.
The existing electorates of Fenner and Canberra will be subject to redistributions to create the new seat, the first time since the late-1990s that Canberra has had more than two lower house representatives.
Electoral Commissioner Tom Rogers said an ACT redistribution committee would be appointed to complete the carve up and the public would be given the chance to make suggestions and comments about the new boundaries.
The ACT government and federal MPs welcomed the move, which ABC election analyst Antony Green said made it unlikely there would be an early election called by the government before late 2018.
He predicted a relatively quick redistribution process in Canberra, expecting shadow assistant treasurer Andrew Leigh's seat of Fenner would be pushed north, with Gai Brodtmann's seat of Canberra centring on Lake Burley Griffin.
The new third seat would then take in Tuggeranong.
"On past voting trends, the new seat would be stronger for the Liberal Party, but like Fenner and Canberra would still be a Labor seat," Mr Green said.
A third ACT seat, the electorate of Namadgi, was created in 1994 and abolished in 1997.
Labor's Annette Ellis held the seat until the 1998 federal election, before moving to the electorate of Canberra.
Mr Green predicted the new seat would take the same name.
Population data from December showed the capital grew by 11.2 per cent in five years to 2016, adding an extra 40,000 new residents and bringing the ACT's population to 406,403 people.
The redistribution process is designed to give each state and territory representation in proportion to its population, and to ensure there are a similar number of voters in each electorate of a given state or territory.
After public suggestions, the redistribution committee will publish an initial decision on where the boundaries will fall, along with reasons for the proposal.
A 28-day objection period will then take place, before written comments about the objections will be received.
Final decisions will go to the Special Minister of State and be tabled in Parliament, which has no power to reject or change the new electorates.
Currently the seat of Canberra, which includes the population of Norfolk Island, is the most populous in Australia, followed by Fenner.
Members of the public will be invited to suggest a name for the new electorate, based on guidelines published by the commission.
Electorates can be named after prominent Australians who have died after giving outstanding service to the nation.
In naming new divisions, the commission favours the names of former prime ministers, while names of geographical features and Indigenous names can also be considered.
The guidelines are not binding.
When the electorate of Fenner was changed from its former name of "Fraser" in 2015, the four-person redistribution committee was split on a proposal to rename Canberra as "Churcher", in recognition of respected Australian arts and cultural figure Betty Churcher who died in 2015.
A casting vote in favour of retaining the existing name settled the dispute, but the proposed name could be considered for the new seat.