Casper Matthee, born in the United States, raised in South Africa, held his citizenship certificate high as he walked through the crowd at Rond Terrace, onlookers calling out to him: "Good on you, mate!".

His wife Svetlana Plotnikova,from Russia, and their South African-born children,Nikolai, seven, and Neena, 11, also became Australian citizens on a warm Canberra day.

The family, now living in Curtin, was overwhelmed by how they had been embraced, including by Ngunnawal elder Tina Brown who performed a smoking ceremony and painted ochre on their face.

"It's emotional. It's one of the best days of our life," Ms Plotnikova said.

Nigerian architect Samuel Udom became an Australian citizen as his 15-month-old daughter Mikaela earlier jigged happily to Along the Road to Gundagai played by the band of the Royal Military College Duntroon.

Mr Udom and his wife Gift brought Australian-born Mikaela back to Nigeria for a visit and it turned out to be "a very interesting" experience.

"In the sense we kind of missed Australia while we were there, that was something new for us," he said.

Janet and John Collins from the United Kingdom were cheered by their dragon boating mates as they became Australian citizens, Mrs Collins saying the tipping point to becoming an Australian was "Ah, Brexit, I think".

The Choir of Hard Knocks sang Absolutely Everybody with gusto. The national flag was also raised and the cannons fired at Regatta Point, rousing the flying foxes in Commonwealth Park. Muslims for Loyalty pledged their love for Australia. The smell of smouldering gum leaves for the traditional smoking ceremony wafted in the air.

At the Canberra ceremony, 28 people from 13 countries were conferred with Australian citizenship, Prime Minister Malcolm Turnbull leading them in their oath.

"What a beautiful, still day here on Lake Burley Griffin and how the echoes of the guns were heard bouncing off the great institutions of our capital," Mr Turnbull told the crowd.

"The Library, the Parliament, the High Court. Reminding us of our democracy, the rule of law, those values which we uphold as thoroughly Australian values here in this great land we call home."

Mr Turnbull said mateship, a fair go, respect, were part of an Australia enriched by cultural diversity, including the contributions of the first Australians.

The country was "at our best and most Australian" when helping others including "the selfless sacrifice of the diggers a century ago, the courage of their descendants in the Middle East today".

"Volunteers fighting fires and floods, pulling kids out of a rip at the beach, rushing to the aid of the wounded on Bourke Street," Mr Turnbull said.

"Together, we have created a remarkable, extraordinary nation"

Governor-General Sir Peter Cosgrove and National Australia Day Council chair Ben Roberts-Smith also addressed the crowd.

"There is no right or wrong way to celebrate Australia Day but, for me, Australia Day is a day of unity," Mr Roberts-Smith said. "A reminder to think about our nation's past, celebrate the present and look confidently towards the future."

Love was a theme for some new citizens. Or amore, to be more precise.

Italian Ruggero Venosi, 25, met his Australian girlfriend Josephine Janssen, 23, while they were both studying at the ANU and that "changed everything". His mother Silvina came from Rome for the ceremony.

"I'll always keep my Italian heritage, never give up my food or my soccer team. But Australia is such an open and respectful country that it pushes me to keep combining both countries and make sure they can both learn from one another," Mr Venosi said.

Dunlop woman Sara Marques Matos, 41, a child care worker from Brazil had much to celebrate - becoming an Australian citizen on Thursday and preparing to marry her fiance David Matschulat on Saturday.

She was enamoured with her new country. "Australia has an endless beauty," she said.

And in the crowd, Henrik Kustra, 91, formerly of Poland stood ramrod straight holding an Australian flag throughout the ceremony, as he does every Australia Day. He has lived in Australia since 1948.

"This country adopted me and I love it," he said.