The Black Eyed Peas frontman made the suggestion when meeting him for a day of promotion for his Prince's Trust charity in London recently.
Charles - who is married to Camilla Parker Bowles - was asked if he had a room free in his Clarence House residence by the DJ.
'The Voice' UK coach - who also starred in the Diamond Jubilee Concert - is looking for a new place to stay in capital city and thought the huge home could cater for him well.
He told The Sun newspaper: "I told Prince Charles I was looking for a flat here and said, 'This is a big old crib you've got here. It's a big old house. So could I get a little space?"
Will.i.am recently gave a £500,000 donation to the organization to help give young people in east London a good start in training and start up businesses.
The 37-year-old said: "The people of the UK welcomed me into their homes every week and I wanted to give something back.
"I called my manager and said, 'What can I do with the money that I'm getting for 'The Voice'? I don't need it'. It's the least I could do - the show changed my life."