Millions of Australians have marked the Australia Day holiday through citizenship ceremonies, celebrations, and protests.

Prime Minister Anthony Albanese and Governor-General David Hurley met with Indigenous elders for a private smoking ceremony as official commemorations kicked off around the nation.

Newly appointed Australians of the Year as well as dignitaries including United States ambassador Caroline Kennedy attended the flag-raising and citizenship ceremony in Canberra.

Mr Albanese said it was the nation’s great pride to have 60,000 years of Indigenous culture and history.

“Today is a difficult day for Aboriginal and Torres Strait Islander peoples, and that is acknowledged,” he said.

“Let us all recognise the unique privilege we have to share this continent with the world’s oldest continuous culture.”

Canberra’s Aunty Violet Sheridan used her welcome to country to call for unity.

“I’m a proud Ngunnawal Aboriginal woman but I’m also a proud Australian,” she said.

“I want us to come together.”

But just kilometres down the road in Canberra’s centre, Indigenous activists were protesting “Invasion Day” as they marched towards the Aboriginal Tent Embassy.

Invasion Day or Survival Day rallies are being held in all capital cities, providing a visual reminder of opposition to the public holiday.

Protest leaders are calling for a focus on sovereignty, treaty and truth-telling, and some rallies heard speakers stridently opposed to the Indigenous voice referendum proposal.

Governor-General David Hurley said Australia had become a country to be proud of since Captain Arthur Phillip landed at Sydney Cove in 1788, one made stronger by the history, traditions and culture of Indigenous people.

“That is worth celebrating. Yes, there are many challenges and yes, we don’t agree on everything.

“We do however work hard, look out for each other and are not afraid to take on the big challenges.”

Events in Sydney began at dawn with a projection on the Opera House by Kamilaroi woman and artist Rhonda Sampson acknowledging the important role of women around Sydney Cove before Captain Phillip’s arrival.

It was followed by a smoking ceremony at Barangaroo, held for the 20th year to celebrate the culture and language of Indigenous people.

The 46th annual Ferrython, a traditional race across the harbour, also took place.

The Andrews government in Victoria cancelled the street parade through Melbourne, choosing to focus on local gatherings.

But a 21-gun salute occurred at midday at the Shrine of Remembrance followed by the RAAF Roulettes city fly-over.

For many people, Australia Day is business as usual.

Deloitte, KPMG, CSL and other large companies have allowed employees to work on Australia Day and take a day of leave at another time as part of their flexible cultural leave arrangements.

Polling from conservative think-tank the Institute of Public Affairs suggested three-and-a-half times more Australians support Australia Day remaining on January 26 than those who were opposed.

But support decreases among younger age groups. Among 18-to 24-year-olds, only 42 per cent were in favour of maintaining the day compared to 30 per cent against.

– AAP