In the page-long feature, which comes after the Prince met an old school friend of his on a visit to The Big Issue offices last year, he says homelessness can happen to anyone.
"Having heard a great deal about The Big Issue from various young people, I was particularly glad to visit its offices recently," the Prince writes in this week's issue of the magazine. "While at the offices I had the great surprise of bumping into Clive Harold, who went to Hill House School with me, and who I know has benefited from the opportunities which The Big Issue has given him. It was a vivid reminder that homelessness can happen to almost anyone."
After meeting the Prince in December Mr Harold described how they had played football together as nine-year-olds at school. He ended up on the streets selling The Big Issue after losing his job and turning to drink.
The Prince of Wales praises the magazine, which is sold by the homeless, saying: "We all owe a considerable debt to The Big Issue, not only because of the valuable chance it provides to some of the homeless people on our streets to take on a real job, but also because it helps to ensure that homelessness is kept at the forefront of our minds."
He adds that homelessness tends to be a symptom rather than a cause of people's problems, resulting from unemployment, low educational achievement and drug or drink problems.
"Even with a supportive home background young people today can find it hard to maintain their self-confidence against the enormous pressures of modern life," he writes.