Canada has unveiled a new $20 banknote featuring a portrait of King Charles III, the first new monarch to appear on a Canadian banknote in more than 70 years, following Queen Elizabeth II's death in 2022.

The banknote was revealed at a Bank of Canada event on Thursday - a "very special day", central bank governor Tiff Macklem said.

A unique feature of the banknote is its vertical orientation. The back features an image of the Vimy Ridge memorial in France, commemorating Canada's role in World War I.

The Commonwealth nations of New Zealand and Australia have displayed the King on their coins, though Australia has said it will not feature him on banknotes.

Instead, Australia said it will work on releasing a new $5 banknote that pays tribute to "the culture and history" of Indigenous Australians to replace the current design featuring Queen Elizabeth II.

Canada is the first Commonwealth country to put the King on its banknotes outside of Britain since his accession to the throne.

In addition, it also depicts a floral and leafy tapestry "inspired by the King's lifetime dedication to the environment", according to the Bank of Canada.

Wayne Long, a Liberal MP and secretary of state for the Canada Revenue Agency, said at the unveiling that the symbols on the banknote "serve as a powerful reminder of who we are as a nation and what we value."

Some elements of it were chosen in consultation with an Indigenous advisory council, the central bank added.

It is the second vertical banknote issued in Canada. The first is the $10 bill, depicting Black civil rights advocate Viola Desmond. Its design was selected as the best in the world in 2018 by the International Bank Note Society.

The new $20 banknote will enter circulation early next year, said Macklem.

Polling suggests that many Canadians believe the country should end its formal ties to the British monarchy, particularly in the French-speaking province of Quebec.

But the monarchy's popularity received a small bump as tensions rose between Canada and the US, including the ongoing US-Canada trade war and US President Donald Trump's comments about making Canada the "51st state".

Prime Minister Mark Carney invited the King to open Canada's parliament in May - a visit that Carney at the time said "clearly underscores the sovereignty of our country".

The King is Canada's head of state and is represented in Canada by its Governor General Louise Arbour.