The singer, 69, has become the first global ambassador of Charles’ Prince’s Trust charity and the pair announced the collaboration in Barbados.
The heir to the throne, 70, couldn’t resist making a play on lyrics from the US star’s hit song Hello.
As Charles thanked him for taking up the role, he said: “It must have been you I was looking for.”
Mr Richie responded in mock horror with: “Oh, did you say that? He did say that”.
In his role as chair of the new Global Ambassador Group, the singer will support the Trust as it sets to work on a new global remit, tackling issues like youth education and unemployment, supporting indigenous youth and helping build sustainable communities.
Speaking at the reception, Mr Richie said: “I’ve been involved with the Prince’s Trust for a number of years and, of course, I understand exactly what they do – giving opportunity to kids who would never ever have a shot at anywhere close to their dreams.”
The Prince’s Trust International was founded by The Prince of Wales in 2015 to share the successful programmes of the Prince’s Trust and reach more young people worldwide.
Charles and Camilla are on a 12-day tour of the Caribbean, with over 50 engagements lined up.
They’ll spend four days in Cuba on their overseas visit – making them the first members of the Royal Family to visit the Communist-run country.
On Tuesday, paparazzi-style pictures of the couple in their swimwear on a public Barbados beach were published online, causing a stir among royal fans.