The photo is believed to have been taken by unauthorised paparazzi.
The Princess of Wales has been photographed for the first time since undergoing abdominal surgery.
Kate was pictured near Windsor Castle on Monday in the passenger seat of a car, according to TMZ.
The news site said she was wearing dark sunglasses in the black Audi which was being driven by her mother, Carole Middleton.
The photo is understood to have been taken by unauthorised paparazzi.
Kate was admitted to the London Clinic – the private hospital where the King underwent treatment for an enlarged prostate – for a planned operation on January 16.
The 42-year-old future queen was last pictured in public during a Christmas Day walk in Sandringham, Norfolk.
