"This is not something that is hereditary," Daniel Westling said during a joint interview with his bride-to-be on the commercial TV4 channel late Monday.
Westling's first public comments about his kidney malfunction aimed to calm fears that the illness could be passed on to the future heir to Sweden's throne.
The 36-year-old former fitness instructor to the princess, said he had been born with the kidney defect but had not realised there was a problem until he needed x-rays after suffering a injury playing football when he was 16.
"It was not something I had suffered from or even noticed," he said.
But doctors had said his condition was deteriorating and about two years ago it was decided that he would need a transplant.
Since the transplant, he said, he felt better than ever.
"My body has been cleansed. I have a new kidney that is cleaning the blood."
Westling is to marry Victoria, 32, the eldest daughter of King Carl XVI Gustaf, on June 19th. After the wedding Westling, who came from humble origins in the small Swedish town of Ockelbo, will be known as Prince Daniel, Duke of Västergötland.