Swedish researchers found men who drank 300ml of a fizzy drink a day - slightly less than a standard can - were 40 per cent more likely to develop the disease than those who never consumed the drinks.
Worryingly, the risk applied not to early-stage disease that was spotted via blood tests but to cancers that had progressed enough to cause symptoms, the 'Daily Mail' reported.
Experts believe that sugar triggers the release of the hormone insulin, which feeds tumours.
The study, published in the American Journal of Clinical Nutrition, is far from the first to link the sugary soft drinks to poor health.
Previous research has flagged up heart attacks, diabetes, weight gain, brittle bones, pancreatic cancer, muscle weakness and paralysis as potential risks.
The new study tracked the health of more than 8,000 men aged 45 to 73 for an average of 15 years. The men, who were in good health at the start of the study, were also quizzed about what they liked to eat and drink.
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At the end of the study, they compared the dietary habits of the men who had been diagnosed with prostate cancer with those who remained healthy and found a clear link between sugary drinks and the disease.
"Among the men who drank a lot of soft drinks we saw an increased risk of prostate cancer of around 40 per cent," Lund University researcher Isabel Drake said.
The analysis also linked large amounts of rice and pasta, cakes and biscuits, and sugary breakfast cereals with a less serious form of the disease. There was no link with fruit juice.
Diet drinks, and tea and coffee with sugar, were not included in the study.
Researchers said that although genetics plays a bigger role in prostate cancer than in many other tumours, diet also appears to be important.
Drake added that more research is needed to prove the link.
British experts also urged caution over the findings.
"We cannot be certain whether any particular dietary pattern has a significant impact on a man's risk of getting prostate cancer but it is highly unlikely that any single food source will lead to an increased chance of developing the disease," Dr Iain Frame, director of research at Prostate Cancer UK, said.