The Sydney-based painter of Dhungatti heritage won the prestigious art prize on Friday for his portrait of Wiradjuri artist Karla Dickens during the Lismore floods.

He is the first NSW Koori to win the $100,000 prize, in a contest that until recently was predominantly won for depictions of white male faces.

"We have smashed this out of the park with this portrait," he told AAP.

"Karla is a female, a woman of colour and a same-sex preference individual, so it's just this trilogy that I never expected in my wildest dreams would be hanging on the walls as a winner."

Titled Moby Dickens, the portrait was unanimously chosen as the winner by Art Gallery of NSW Trustees.

The win is symbolic of a cultural shift towards greater inclusion and diversity in the commercial art world, Mr Douglas believes.

"I didn't anticipate that this would happen as soon as it has and so it's a tremendous legacy not only on behalf of this institution but others who are seeking to change the landscape," he said.

Ms Dickens' heroic efforts during the floods in her hometown of Lismore inspired the portrait.

"It just so happens that I was there in Lismore immediately after the first deluge in January and saw the shock and horror on people's faces," he said.

She had reached a pivotal point in her own art career when the flood catastrophe happened.

"When she should have ordinarily been excited about where her career was going, she was harbouring three families in Lismore as part of her own rescue mission," he said.

Mr Douglas is a five-time Archibald finalist and was also a finalist in the Wynne Prize in 2009.

He was among 52 finalists whose work included portraits depicting Hollywood actor Hugh Jackman and former politician and Midnight Oil frontman Peter Garrett among others.

A self-portrait by last year's winner Peter Wegner, a seven-time finalist from Melbourne, was also in the running.

The judges highly commended Jude Rae for her portrait of Dr Saul Griffith.

This year's $40,000 Sulman Prize for the best subject or genre painting was awarded to Claire Healy and Sean Cordeiro for their work titled Raiko and Shuten-doji.

The $50,000 Wynne Prize for Australian landscape paintings was awarded to Nicholas Harding for Eora.

There were more than 1900 entries across the three prizes, including a record number from Aboriginal artists. There was also a record number of Aboriginal finalists across the three competitions.

Sydney artist Claus Stangl, who created a 3D portrait of Kiwi film director Taika Waititi, took out the $3000 Packing Room Prize, a category awarded by gallery staff who receive, unpack and hang the portraits.

The exhibition of finalists opens on Saturday and runs until August 28.

Australian Associated Press