Danny Dyer has joked he was having a "family reunion" when he met Prince Charles at the Prince's Trust Awards.
The EastEnders star found out he was related to royalty when he filmed Who Do You Think You Are in 2016.
Dyer introduced himself to the prince as a "relative", telling him "King Edward III is my grandfather".
The prince told the audience that he had "discovered a long-lost relation with Daniel Dyer" and said he would be doing "some research" into it.
While filming Who Do You Think You Are, Dyer found out he was related to Thomas Cromwell, Edward III, William the Conqueror and Henry III.
He went on to present a two-part series, Danny Dyer's Right Royal Family, where he got know his royal ancestors and experienced how they lived.
The actor was at the Prince's Trust Awards to present the mentor of the year award.
When he was introduced to the prince he told him: "I'm in EastEnders. Just wanted to let you know we're related as well. King Edward III is my grandfather - but I won't go into it. No he is, on my life."
The prince replied: "A very long way away."
Later on on stage Charles told the audience he had "discovered a long-lost relation with Daniel Dyer".
"He told me he was descended from Edward III, which is interesting. I must do some research when I get back," he said.
Dyer joked with the audience that he was having a "family reunion" with Charles.
"When your cousin Charlie makes the call, you've got to help your family out, you know what I mean?" he said.
He also joked that his reference to their family connections went over the prince's head, saying it went "straight up his nut".