The Queen will miss the Commonwealth Heads of Government Meeting (CHOGM) for the first time since 1973 as the amount of long-haul travel she undertakes is reviewed.
The Prince of Wales will represent the Queen, who is the head of the Commonwealth, at the event in Sri Lanka in November, Buckingham Palace confirmed.
A spokesman said: "I can confirm that the Queen will be represented by the Prince of Wales.
"The reason is that we are reviewing the amount of long-haul travel that is taken by the Queen."
Many will see the decision as part of a move to transfer some responsibilities to her heir.
The monarch was admitted to hospital earlier this year suffering from the symptoms of gastroenteritis.
She was forced to cancel her appearance at the Commonwealth Day service at Westminster Abbey in March while she recovered from the illness.
And unless the CHOGM event is staged in Britain in 2015, many will ask whether the Queen, who by then will be 89, is likely to attend another such meeting in her lifetime.
The leaders of 54 Commonwealth nations meet every two years to discuss and agree collectively on global issues.
The Queen attended the last CHOGM meeting in Perth, Australia, in 2011.
Last year saw younger generations of the royal family represent the Queen overseas as part of her Diamond Jubilee celebrations.
Some are likely to predict this latest development will pave the way for Prince Charles becoming the next head of the Commonwealth, despite the role not passing automatically to the Queen's eldest son.
It also follows comments from Australia's Prime Minister, Julia Gillard, supporting Charles taking over the Commonwealth role despite preferring to move to a republic once the Queen is no longer on the throne.
"For Australia's part, I am sure the Queen's successor as monarch will one day serve as head of the Commonwealth with the same distinction as Her Majesty has done," Ms Gillard said in March.
In a television message recorded in Cape Town on her 21st birthday, the then Princess Elizabeth told the Commonwealth: "I declare before you all that my whole life, whether it be long or short, be devoted to your service and the service of our great imperial family to which we all belong."
Buckingham Palace said the Queen's decision not to attend was not related to sensitivities surrounding Sri Lanka's human rights record, which has led to Canada's Prime Minister Stephen Harper to boycott the CHOGM.
The spokesman said: "It is nothing to do with the political situation in Sri Lanka.
"The key point here is that the Queen will be represented, although she is not there in person, by the Prince of Wales."
Mr Harper has demanded an inquiry into allegations that up to 40,000 civilians were killed by Sri Lankan troops during the war with Tamil rebels.