The British Normandy Memorial records the names of the 22,442 servicemen and women under British command who died during the D-Day landings and the Battle of Normandy in the summer of 1944.
Designed by British architect Liam O'Connor, the structure has been built at Ver-sur-Mer in France and its opening is being livestreamed to those who cannot attend due to Covid-19 restrictions.
Veterans and their families gathered at the National Memorial Arboretum in Staffordshire on Sunday to watch the event remotely and to mark the 77th anniversary of the D-Day landings.
The Royal British Legion s assistant director for commemorative events, Bob Gamble, said: "D-Day remains one of the most remarkable Allied wartime operations in history, and it is our great privilege to have brought so many of our Normandy veterans and their family members together to mark the 77th anniversary of the landings.
"It remains as important as ever for us to remember and pay tribute to the immense bravery and sacrifice shown by all who served and fell during the Battle of Normandy."
The memorial, which cost almost £30 million and was funded by the British Government and private benefactors, stands on a hillside overlooking Gold Beach, one of three where British forces landed on the morning of June 6 1944 to begin the liberation of Western Europe.
The Prince of Wales, patron of the Normandy Memorial Trust, said he had wished to travel to France and spoke of his pride at opening the "remarkable" memorial.
He said in a video message: "I know just how much our incomparable veterans had hoped to be in Normandy today to see their memorial for themselves.
"Despite having to watch via satellite link, this in no way obscures the enormous regard, and admiration, in which we hold our veterans or diminishes our debt of gratitude to the more than 22,000 men and women whose names are now permanently inscribed in stone in this place of honour above Gold Beach."
Meanwhile, Prime Minister Boris Johnson also paid tribute to those who fought in D-Day, tweeting: "As General Eisenhower said, when Allied troops landed on Normandy's beaches that June morning in 1944 the eyes of the world were upon them.
"The hopes and prayers of liberty-loving people everywhere marched with them. 77 years on, we thank and remember them. "
The memorial features the D-Day Sculpture by British sculptor David Williams-Ellis, the D-Day Wall featuring the names of those who fell on D-Day itself and, on 160 stone columns, the names of those others who lost their lives between D-Day and the Liberation of Paris at the end of August 1944.
The site also includes a French memorial dedicated to the memory of French civilians who died during the period.