The 62-year-old was freed after more than two years behind bars following a successful parole bid.
"I'm very happy to be out. It's a beautiful day to be free," he said, speaking to reporters from a car on his way out of Canberra's Alexander Maconochie Centre on Thursday.
The former army lawyer was sentenced to a maximum of five years and eight months in jail in May 2024 after he helped steal secret defence documents about the Afghanistan war and leaked them to the media.
McBride aimed to expose intense investigation of Australian soldiers in Afghanistan, but it was revealed soon after defence personnel had been involved in illegal killings while on the frontline.
He pleaded guilty to three charges, including theft.
"I'm looking forward to seeing my dog and my daughters ... hopefully my dog will remember who I am," he said upon release.
He declined to answer questions about Australia's whistleblower laws, saying he wanted to be fair to Attorney-General Michelle Rowland who had just approved his parole.
McBride will be allowed to serve the last three years of his sentence in the community under supervision and strict conditions.
In a statement, he thanked his family for not giving up support and for providing inspiration while in custody.
"I'd like to thank all my amazing supporters from around both Australia and the world who sent me such inspirational messages," he said.
"Many thanked me for allowing them to believe in this country again. In turn, I thank them for showing me there are so many good people in the world worth fighting for."
McBride, who revealed he has lung cancer, served his full non-parole period of 27 months and was granted release the same morning he became eligible for it.
His long-time supporter MP Andrew Wilkie, a former intelligence officer, said the ordeal was emblematic of "weak legal protections and a succession of antagonistic governments" in Australia.
"(The governments) seem to think it's better to punish whistleblowers and deter their colleagues, than to celebrate them and respond to their concerns," Mr Wilkie said in a statement.
The news was also celebrated by Greens senator David Shoebridge, who said McBride should have walked free long ago.
"My friend David McBride has paid a terrible price for saying the truth. It's a price no whistleblower should ever be made to pay again," Senator Shoebridge said in a statement.
Whistleblower Justice Fund founder and former senator Rex Patrick said McBride had been brave in exposing war crimes.
"It's so good to see the end of an awful saga that should never have happened. I salute David who walks away from prison with his head held high," he said.
ACT corrective services will continue to monitor McBride in the community, a territory government spokesperson said.
McBride confirmed he was due to have a cancer operation in coming weeks.
The father-of-two said prison had been a "hard but good" experience, for which he praised prison staff.
"The corrective services were very professional, very polite to me, and the prisoners were good too," he said.
"It was, on the whole, a very positive experience. I'm happy to be out though."
11°C