The 33-year-old refugee and criminal lawyer shed tears as he received the top honour from Premier Mike Baird at ceremony in Sydney on Monday night.
He said he was beyond surprised.
"Shocked," he said.
"I never dreamed of anything.
"Even (being) a fisherman."
Mr Adut was forced to fight as a child soldier at the age of six in Sudan before he was smuggled out and made it to Australia.
From illiterate refugee to criminal lawyer, Mr Adut is studying for a second master's degree while running AC Law Group, which he set up to fight for members of the Sudanese community from his home in Blacktown in Sydney's west.
His story is well known, largely thanks to a TV advertising campaign for Western Sydney University, which depicts his remarkable story.
Mr Adut said Australia was not his adopted country, but his home.
"You are not Australian because you are born in Australia. You are Australian because Australia is born in you," he said, re-wording an African saying.
There's a list of issues close to his heart which he hopes to advocate for if given the opportunity as Australian of the Year - domestic violence prevention, juvenile justice, discrimination and inclusiveness.
"Children shouldn't be going to jail," he said.
"I'd like to be working with kids in jail to help them transition into the workforce.
"I'll make sure I work with schools.
"One day I'll be able to visit every single school in Australia and be able to tell my story."
Mr Adut was joined on Monday night by celebrity doctor John Knight, better known as James Wright, who took out NSW Senior Australian of the Year and reconciliation champion Arthur Alla, 27, who won NSW Young Australian of the Year.
"These individuals have pursued their passions, helped so many people and as a result made us all proud," Mr Baird said.
The national awards will be held in Canberra on January 25.
