The Duke of Cambridge, 39, went out on the streets of Rochester Row, near Victoria in London, with The Big Issue vendor Dave Martin to sell copies of the magazine to members of the public.
The news quickly went viral, and the young royal has now appeared on the front cover of the latest issue.
In a new article penned for the publication, Prince William has said selling copies of The Big Issue was “eye-opening” after he spent the day doing so earlier June.
Prince William has also praised his late mother’s “inimitable style” in the letter for the publication, as he recalled the first time he visited a homeless shelter with the late Princess Diana.
“I was 11 when I first visited a homeless shelter with my mother, who in her own inimitable style was determined to shine a light on an overlooked, misunderstood problem,” he wrote, as he explained why he decided to spend the day selling copies of the magazine.
The duke said he “refuses to believe” that homelessness is an “irrevocable fact of life”.
“It is an issue that can be solved, but that requires a continued focus and comprehensive support network,” he added.
Prince William added that he has always believed in using his platform to “help tell those stories and to bring attention and action to those who are struggling. I plan to do that now that I'm turning 40, even more than I have in the past.”
Watch: Prince William says he will take his children to work at homeless shelters
The Duke of Cambridge partnered with The Big Issue to celebrate his 40th birthday on Tuesday 21 June, which he felt was “a good opportunity” to highlight something that matters to him.
“I wanted to make sure we were highlighting something that matters to me, he revealed in another article for the publication. “Off the back of Everyone In [the scheme that brought all rough sleepers off the streets during the pandemic] it started to feel that actually, this issue isn’t quite as big to tackle as we think. But it feels like it’s gone back to what it was before the pandemic.
“We can fix it. It is possible to – I never want to say completely end homelessness, because every day something else might happen for someone – but get on top of it more than we have done.”
He added that he hopes to introduce his children, Prince George, eight, Princess Charlotte, seven, and Prince Louis, four, to organisations such as The Big Issue, as his mother did with him and Prince Harry.
“In the years ahead, I hope to bring George, Charlotte and Louis to see the fantastic organisations doing inspiring work to support those most in need – just as my mother did for me,” the Duke wrote.
“As she instinctively knew, and as I continue to try and highlight, the first step to fixing a problem is for everyone to see it for what it truly is.”