Meshael Alayban, 42, arrested on Tuesday, is one of the wives of Saudi Prince Abdulrahman bin Abdulaziz bin Nasser al Saud.
A Kenyan woman, who has not been named, was seen in distress while carrying a suitcase down a road, and flagged down a bus. She told a passenger she believed she was a human trafficking victim, and the passenger called the police.
The 30-year-old woman was hired in Kenya in 2012 and her passport was taken from her on arrival in Saudi Arabia, authorities say. According to the prosecution, she was forced to work inhuman hours, given less pay than promised and forbidden from leaving.
The prosecution said the alleged victim was working "around the clock" for the family, cooking, cleaning and caring for children, paid only about $200 a month. She had allegedly signed a contracted with an agency promising her $1600.
District Attorney Tony Rackauckas charged Alayban with one count of human trafficking, and if convicted, she faces up to 12 years in prison.
"This is not a contract dispute," he said. "This is holding someone captive against their will."
Alayban, who has been given a $5m bail and a ban on leaving the country, did not attend court. Her lawyers say the case is a "domestic work hours dispute".
Rackauckas voiced fears that no amount of money set by the judge would be unaffordable to a Saudi princess, and asked the judge to deny bail.
Four other women employees left the house when police arrived, having travelled to the US with the family, US authorities said.