Hassa bint Salman, a daughter of King Salman and sister of the powerful Crown Prince Mohammed bin Salman, had been charged with instructing her bodyguard to beat up a plumber.
Tried in absentia and the target of an arrest warrant since December 2017, she was also ordered by the Paris court to pay a €10,000 fine.
The princess, 42, had never shown up at the trial, which got underway in July.
The punishment was heavier than demanded by prosecutors, who had sought a six-month suspended sentence and a fine of €5,000.
The princess, whose brother is known by his initials MBS and is seen as the kingdom's de facto ruler, was accused of instructing her bodyguard Rani Saidi to beat up Ashraf Eid after he was seen taking pictures inside her home in September 2016.
She had been charged with complicity in an act of intentional violence, complicity in illegal confinement and complicity in theft.
Saidi, who was the only protagonist in the case present in court, was handed an eight-month suspended sentence and a €5,000 fine, in line with the recommendations of prosecutors.
Eid was working on the seventh floor of the luxury apartment block owned by the Saudi royals on Avenue Foch, a favourite destination of foreign millionaires in Paris, when he was called to the fifth floor to repair a damaged wash basin.
He took pictures of the bathroom which he told investigators he needed to carry out his work.
Eid claims that the princess flew into a rage after he caught her reflection in a mirror on camera. She called in her bodyguard, who allegedly beat him.
Eid claimed he was also tied up and ordered to kiss the feet of the princess, who is lionised in the Saudi state-run media for her charity work and women's rights campaigning.
The plumber claimed that he was allowed to leave the apartment only after several hours, during which his phone was destroyed, and that at one point the princess shouted: “Kill him, the dog, he doesn't deserve to live.”
The case is the latest blow to the image of the kingdom, where Prince Mohammed sparked hopes of major social and economic reform when he was elevated to crown prince in 2017.
But his reputation was badly damaged by the murder of dissident writer Jamal Khashoggi at Saudi Arabia's consulate in Istanbul last year, and he is also seen as the driving force in the Saudi military intervention in Yemen, where tens of thousands have died.