The Department of Home Affairs and Territories subsequently announced in 1927, on behalf of the Federal Capital Commissioners (FCC), the creation of a competition for the design of the arms.

35 entries were received, with a modified version of a design by Sydney resident Charles Roxburgh Wylie selected and sent to the College of Arms in London for approval.

[3][11] In 2024, the ACT government confirmed that the coat of arms was displayed incorrectly on many buildings, with the position of the black and white swan reversed.

In 1932 the Australian High Commissioner to London sought advice from the College of Arms, which advised that the Commonwealth Government is the legal successor.

"[13] The blazon (formal heraldic description) of the arms is as follows:[18] [Arms:] Azure a triple towered Castle, between in chief a Sword of Justice point upwards to the sinister Argent Pomel [sic] and Hilt Or surmounted by a Parliamentary Mace head upwards to the dexter Gold in saltire charged at their point of intersection with a representation of the Imperial Crown proper and in base a Rose also Argent, barbed and seeded proper (being the Badge of York).

However, following the adoption of the southern brush-tailed rock-wallaby as the mammal emblem for the territory in 2018, an inquiry was held into the creation of new coat of arms.

Many of these designs included depictions of bogong moths, gang-gang cockatoos, southern brush-tailed rock wallabies, a royal bluebell, the Federation Star, representations of Parliament House and an Indigenous symbol for a meeting place.