Ryan Tubridy spoke about how surprised he was when he found out about his family's direct link to British monarch Edward III.
The revelations came out during the filming of RTE TV series of Who Do You Think You Are.
Tubridy got a message on his radio programme this morning asking if he was related to the royals.
He went to speak about his part in the TV show that discovered that fact about his lineage which was shown over a decade ago.
Ryan's great-great-great grandmother Frances Dolman was a well-bred Englishwoman and a member of "the Yorkshire aristocracy".
The Dubliner was told that Frances's lineage went all the way back to the 15th century and King Edward III, King of England and France.
He said this morning on RTE Radio One: "So we made Who Do You Think You are. (several years ago)
"We talked about my grandfather from Dublin in the Civil War.
"We went to the hills of Connemara to see my other grandfather who was shall we say a political activist at the time, in that area.
"It was all very green."
The makers of the programme told Tubridy they were going to London.
"It was a bit of a hoot for them, it was mildly embarrassing for me.
"There was a bit of a laugh all round, great programme and great fun."
Both of Ryan’s grandfathers were Republican volunteers – one in Galway and the other in Dublin.
Tubridy's paternal grandfather, the doctor and TD Sean Tubridy, had a turbulent time after the Civil War in Ireland.
Epidemics of cholera, typhus and the Spanish Flu were rife in Connemara, Co Galway, at the start of the 20th Century.
Dr Sean Tubridy played an important role in helping to battle these outbreaks.
His maternal grandfather Todd Andrews also fought in the Civil War and was a high profile civil servant.
Late Late Show host Ryan was born and raised in Blackrock, Co Dublin.
