She was rescued unharmed by FBI agents and police in Baltimore following a week-long international manhunt.
Her mother Sandra Boss, who lives in London, almost fainted with relief when she was told the news that the daughter she nicknames "Snooks" was safe.
The girl had been abducted during a supervised visit to her father Clark Rockefeller, 48, in Boston.
He has been arrested on kidnapping charges and is expected to appear in court on Monday.
US detectives are investigating his past after it was revealed during the hunt that no record of his existence could be found before 1995 and he used a string of aliases.
Rockefeller was caught after the real estate agent who leased him a property in Baltimore tipped off police.
The FBI watched the house for five hours and then lured him out by telephoning him and saying his 26ft catamaran, which he had docked at a nearby marina, was taking on water.
They then quickly arrested him and found his daughter inside the property.
Ms Boss, a London-based partner in global management consulting firm McKinsey, first spoke to her daughter on the telephone before flying from Boston to Baltimore for an emotional reunion.
On the telephone Snooks told her: "Daddy left me alone but these nice people came to get me."
Rockefeller had no social security number and was described by police as a "ghost". He was believed to have a passport under the name Michael Brown.
The famous Rockefeller dynasty, which made its fortune from oil, says he is not related to them and police are trying to establish whether Clark Rockefeller is his real identity.
He was a former director of Boston's exclusive Algonquin Club but resigned from the club three months ago.
Ms Boss is a Harvard graduate who has worked with New York Mayor Michael Bloomberg and met Rockefeller while she was working on Wall Street.
