He has taken over patronage of the Royal British Legion from the late Queen ahead of next month’s commemorations.
Buckingham Palace last night revealed that Charles will take on more than 300 of her patronages and charities.
It takes the number affiliated with the King to 669 — including the Legion, which had his mother at its head for more than 70 years.
Sources say “it’s the clearest indication” he will be in Normandy despite his cancer battle.
The Legion is organising D-Day events in France and Portsmouth.
Charles is still undergoing cancer treatment but is now expected to be cleared as fit enough to travel across the English Channel for the occasion.
He is set to stand with French president Emmanuel Macron at the British Normandy Memorial on June 6.
A spokesman for Buckingham Palace declined to comment.