Prosecutors allege Princess Hessa bint Salman became enraged when she saw the plumber allegedly capturing her image, fearing the pictures could be used to harm her as the Saudi monarch's daughter due to her country's conservative traditions.
She left France shortly after the September 2016 incident and was not present for the one-day trial. A warrant for her arrest had been issued in December 2017.
The princess is charged with complicity in violence and sequestration and theft of the plumber's telephone. The body guard, Rani Saida, is charged with violence and sequestration and theft. The plumber was allegedly held for three hours at the residence on a posh avenue near the Champs-Elysees.
The presiding judge, quoting from prosecution evidence, said the princess allegedly told her bodyguard to disparage the workman, calling him a "dog who doesn't deserve to live."
The French-Egyptian plumber, Ashraf Eid — also not present at the trial — told Paris police the bodyguard tied him up at the princess' bidding after he photographed a room to help in returning furniture to its original layout once he finished his work.
"The princess noticed that her face was reflected in the bathroom and that she had been filmed. She called me a dog and called her bodyguard saying in Arabic, 'This one, take his phone. He filmed me,'" Eid reported to police investigators.
Eid said the bodyguard broke his phone and made him kiss the Saudi princess' feet while his hands were bound behind his back.
Saida denied being physically aggressive, but said it is widely known that no one is supposed to photograph the princess and alleged Eid "knew very well what he had done."
"There are 20 or 30 witnesses inside the apartment who can testify that at no time was (the workman) touched," he said, adding that breaking Eid's phone was "the biggest mistake."
"It deprives us showing that this gentleman took videos intentionally," Saidi said.
The prosecutor asked the court to convict the princess and sought a six-month suspended sentence and a 5,000-euro fine. He sought an eight-month suspended sentence for the bodyguard plus a 5,000-euros fine.
The princess "is the authority" at the residence, the prosecutor said. "She is at the origin of what happened."
Violence was medically proven and sequestration was "manifest," he argued.
The princess' lawyer, Emmanuel Moyne, said his client should be acquitted, saying that in her absence "you can have her say anything."
The verdict is expected at a later date.
Associated Press writers Thomas Adamson and Elaine Ganley in Paris contributed to this report.