Terence Darrell Kelly, 36, on Monday admitted taking the four-year-old from a tent at the remote Blowholes campsite last year.
He faced a magistrate via videolink from custody, pleading guilty to forcibly taking a child under 16.
The matter has been adjourned to Perth District Court on 20 March.
Kelly is also facing other criminal charges, including assaulting a public officer. Those matters have been adjourned to a later date.
He remains in custody.
Cleo was found alive and well in early November, 18 days after she went missing from the campsite.
She was rescued from a property just minutes from her family home in the nearby town of Carnarvon, almost 1,000km north of Perth.
Police forced entry to the home and found the little girl alone in a room, physically unharmed and playing with toys.
Kelly was arrested on a nearby street around the same time. He is alleged to have acted alone and is yet to enter a plea to his other charges.
Police have said he has no connection to Cleo’s family.
Kelly was shackled and accompanied by armed riot squad guards on a charter flight from Carnarvon to Perth after his first court appearance.
The extra security was put in place after Kelly was twice hospitalised with self-inflicted injuries while in custody.