Ms Giuffre, who claims she was forced into having sex with Prince Andrew when she was 17, will appear on the BBC's Panorama programme on Monday.
The Duke and Duchess of Sussex travelled to the singer's £15m villa in Nice by private jet.
The Duchess of Sussex is said to have flown to the Spanish island to celebrate her birthday with her husband and son.
The Duke of Sussex discusses environment, responsibility and climate change in an interview with Dr Jane Goodall in British Vogue.
Kate and William's eldest child proudly wears Three Lions on his shirt, in new photos to mark his sixth birthday.