CBS News correspondent Richard Roth reports that the royal heir spent a below-freezing night in an alleyway under Blackfriars Bridge, which crosses the Thames, last week.
His only companions were Seyi Obakin, the chief executive of British homeless charity Centrepoint, and his private secretary. William has been the charity's patron since 2005.
"I cannot, after one night, even begin to imagine what it must be like to sleep rough on London's streets night after night," William said Tuesday. "Poverty, mental illness, drug and alcohol dependency and family breakdown cause people to become and then stay homeless.
"I hope that by deepening my understanding of the issue, I can help do my bit to help the most vulnerable on our streets."
William, second in line to the throne, was exposed to some of the hardships found on London's streets when his mother, Princess Diana, took him to a shelter in 1996. Just 13 at the time, William spent an hour at the facility with his younger brother, Harry.
Diana was well-known for her charitable work and the homeless was a group she was particularly close to. She had also served as Centrepoint's patron, a position she held at the time of her death in 1997.
A photograph released by the charity shows William, 27, in the alley in jeans, a gray hooded sweat shirt and a knit hat pulled low.
In a post to the charity's Web site, Obakin said the idea for William to spend a night on the streets - known as "sleeping rough" in Britain - was hatched in March.
"He was determined, as he has always been, to understand deeply the full range of problems a homeless young person might face," Obakin said. "For me, it was a scary experience. Out of my comfortable bed. Out there in the elements. Out there on an extremely cold night, with temperatures down to -4 C (39 F). And it was the same for Prince William. But he was determined to do it."
Obakin said they found a secluded spot - tucked away behind some garbage bins - and settled in for a restless night.
"But there was no shielding from the bitter cold, or the hard concrete floor, or the fear of being accosted by drug dealers, pimps or those out to give homeless people a 'good' kicking," Obakin said.
William is currently training to be a Royal Air Force search-and-rescue pilot.