Six photographers are standing trial for invasion of privacy after the semi-nude photos were splashed in French, Irish and Italian magazines in 2012.
The photographers deny snapping the images.
In a statement read to the court, Prince William said: "My wife and I thought that we could go to France for a few days in a secluded villa. The clandestine way in which these photographs were taken was particularly shocking to us."
The paparazzi took the photos standing about a half mile away from the location. The villa is owned by his uncle, the Earl of Snowden, Viscount Linley.
Prince William said the topless photos are "all the more painful" given the fate of his mother, Princess Diana, who was killed as her car fled paparazzi in Paris 20 years ago.
She was hounded relentlessly by photographers everywhere she went.
On one occasion, on a skiing trip with Prince William and Prince Harry, she confronted the photographers.
“As a parent, could I ask you to respect my children's space? Because I brought the children out here for a holiday and we'd really appreciate the space,” she said.
Twenty years later, the royals are still asking for that space.