Prowse claims his contract for Return of the Jedi included a share of profits on the film, and although it grossed $475 million on a $32 million budget, Prowse explained in an interview in 2009 that he has never received residuals for his performance. Due to "Hollywood accounting", the actual profits are sent as "distribution fees" to the studio, leaving nothing to distribute to others.
Prowse publicly declared his support for the United Kingdom Independence Party in the 2009 European Parliament election: "I've looked right and left and right again and the only party I can safely vote for is UKIP," and "I have two messages for those considering how to vote. Firstly, stop, look and listen to what is being said. Only UKIP is actually telling us the truth about the European Union and why we need to leave it. Secondly, may June the fourth be with you."
In March 2009, Prowse revealed that he was suffering from prostate cancer and has undergone radiation therapy since the beginning of 2009 at the Royal Marsden Hospital in South London. He discovered that he had the cancer following his participation in a charity event in aid of a prostate cancer charity, where a representative of the charity asked whether, as a man over 50, he had had a PSA test. The conversation stayed in his mind, and on a future visit to a general practitioner, he requested the blood test that eventually led to diagnosis. In 2009 he was still in remission.