"The parents are going to have to negotiate all important decisions regarding Laura with the child protection services," a statement from the court said.
"This means that Laura cannot start her round-the-world trip without their [child protection services'] agreement."
The children's court in Utrecht, the Netherlands, placed her under the care of social services for two months, while psychologists and child protection authorities examine how she would cope with such a journey.
Born on a yacht
Peter de Lange, Dekker's lawyer, said he was confident that her trip would eventually go ahead.
"She is happy with the ruling, and now we can prepare this [journey] in a mature and responsible way," he said.
The court said Dekker, an experienced sailor who was born at sea on her parents' yacht in New Zealand, could remain living with her father, who will share custody with the state.
De Lange said the ruling supports the idea that "you are not a bad parent if you try to help your child fulfill her dream".
Dekker, who according to local press received her first yacht at the age of six, sailed solo to England earlier this year, where she was briefly detained by authorities.
She told Dutch television: "Since I was 10 years old, I've known that I would like to sail around the world".
"I want simply to learn about the world and to live freely."
Her father, Dick Dekker, previously told a local newspaper that he was aware that the voyage was "a dangerous undertaking" but one within her capabilities.
"We would not let our child do something of which she was not in complete control," he said.