Terence Kelly pleaded guilty on Monday to abducting four-year-old Cleo Smith from her family's camping tent on Australia's west coast last year.
The 36-year-old, now with a shaved head and a beard, appeared in Carnarvon Magistrates Court by video link from Perth’s maximum security prison, Casuarina.
He wore a grey t-shirt and said nothing other than entering his guilty plea.
He faces a potential sentence of up to 20 years in prison and will be sentenced in a Western Australian state District Court in Perth on March 20.
On Oct 16, Cleo was camping with her mother Ellie, sister Isla and step-father Jake Gliddon at the Quobba Blowholes near Carnarvon, in the north of Western Australia, when she vanished from her family’s tent along with her sleeping bag.
After a massive 18-day search by land, air and sea that included bounty hunters chasing a million-dollar reward, Cleo was found alone in Mr Kelly’s house just streets away from her family home in November.
The search for her had captivated Australians, and the police who found her wept with relief when they asked who she was and she replied, "My name is Cleo."
Police have said the man arrested soon after Ms Smith's rescue was a stranger to the girl and her family, but they have given little other information about why he was a suspect.
Some details have emerged about Mr Kelly in the press, including his obsession with Bratz dolls. It was later revealed he had dozens of the dolls in his home.
He was reported to be a regular customer at a local toy store where he asked to have dolls wrapped for his “daughters”.
Social media posts by Kelly on pages dedicated to the dolls made reference to his “family”, but he did not have a partner or children.
Kelly has not entered a plea to other criminal charges he faces, including assaulting a public officer. Those charges have been adjourned to a later date.
He is alleged to have acted alone and police say he does not have any connection to the family.
Ms Smith's family has not spoken out publicly since initially expressing thanks to the community and asking for privacy after her safe return.
Last week it was announced that Nine Network will pay almost A$2 million (£1.06 million) for an interview with the Smith family in what is believed to be one of the biggest deals in Australian media history.
Esther Mingo, Mr Kelly’s grandmother, told media outside court before the hearing that she hoped her grandson would “open his mouth up” and reveal the “truth”.
“He’s got stacks of family... Where are his mother and father, why don’t they come here?” she said.
She declined to speak after the hearing.
MP Vince Catania, who represents the region in Western Australia’s state parliament, said the guilty plea was a huge relief for the small, coastal town.
“I think this is the start of the healing process for the family, Cleo [and her parents] Ellie and Jake, but also the community of Carnarvon and the whole of Western Australia,” he told local media.