The 42-year-old royal was 15 when Diana was killed in a high-speed Paris car smash in 1997 after years of being renowned for her support for charitable causes.
In a newly released trailer for an upcoming documentary called Prince William: We Can End Homelessness, the heir to the British throne revealed how Diana's philanthropy is still giving him a boost.
"I've slowly tried to work out what can I bring to the role and the platform that I have," he said.
"I have taken some inspiration and guidance from what my mother did, particularly with homelessness."
Before her death in 1997 at 36, Princess Diana was known for her philanthropic work. (AP PHOTO)
William is helping fight homelessness with his Homewards initiative, and another section from the documentary trailer shows him talking with football player Fara Williams, 40, who experienced homelessness for six years.
"You played for England and Chelsea whilst you were homeless," the prince told Williams in the documentary.
"I don't believe we should be living with homelessness in the 21st century."
William's documentary follows Homewards in its first year as the charity works to demonstrate it is possible to end homelessness.
Launched by William and The Royal Foundation of The Prince and Princess of Wales, the initiative says its mission is to make homelessness "rare, brief and unrepeated" within the next five years.
"Homewards aims to give people across the UK hope that homelessness can be prevented by showing them the progress we can make when we collaborate," Prince William said in a statement.
"It's a big task, but I firmly believe that by working together it is possible to make homelessness rare, brief and unrepeated, and I am very much looking forward to working with our six locations to make our ambition a reality."
As a child, William and his younger brother Prince Harry, 40, would visit homeless charities with their mother as she wanted to expose them to the plight of others not born into privilege.
Diana was also a patron of Centrepoint, Britain's leading youth homelessness charity.