The 75-year-old monarch, who became king in September 2022 after the death of his mother Elizabeth II, was admitted for surgery for a benign prostate condition in January but was subsequently diagnosed with an unrelated cancer.
King Charles III says he will continue to serve “to the best of my ability” after his cancer diagnosis, saying his faith in its potential “remains as sure and strong as it has ever been”.
The 75-year-old monarch, who became king in September 2022 after the death of his mother Elizabeth II, was admitted for surgery for a benign prostate condition in January but was subsequently diagnosed with an unrelated cancer.
The video message will be broadcast on Commonwealth Day, as the Queen leads the Royal family for the annual service at Westminster Abbey.
The king, who recorded the message at Windsor Castle last month, will speak on the topic of “resilience”, to say that the Commonwealth must “find ways of healing” and “pursue solutions” to the “inequalities and injustices which still resonate to this day”.
The theme for the 2024 service is One Resilient Common Future: Transforming our Commonwealth.
Nigerian-British poet and writer Sir Ben Okri will read a poem commissioned for the 75th anniversary of the Commonwealth and there will be musical performances from singer Calum Scott and dance troupe The Ghetto Kids.
Speaking on the 75th anniversary of the organisation on Monday, the King will say: “Having recently celebrated my seventy-fifth birthday, it warms my heart to reflect on the way the Commonwealth has been a constant throughout my own life – a precious source of strength, inspiration, and pride.
“In recent weeks, I have been most deeply touched by your wonderfully kind and thoughtful good wishes for my health and, in return, can only continue to serve you, to the best of my ability, throughout the Commonwealth.
“My belief in our shared endeavours and the potential of our people remains as sure and strong as it has ever been.
“I have no doubt that we will continue to support one another across the Commonwealth as, together, we continue this vital journey.”
The king is currently continuing his state duties from home, having received medical advice to temporarily step back from public engagements while he receives treatment for cancer.
His family, including the Prince of Wales, will attend the Westminster Abbey service in person. The Princess of Wales remains at home recovering from abdominal surgery.
The Duke of York will miss the occasion, as he is no longer a working member of the family. The Duke and Duchess of Edinburgh, Princess Royal, Duke and Duchess of Gloucester and Duke of Kent are due to attend.
The King will hail the diversity of the Commonwealth, saying it is “our greatest strength” in the face of serious challenges including “climate change, the loss of nature, or the social and economic changes that new technologies are bringing”.
“All of this means that we must work together to understand each other’s perspectives, including the inequalities and injustices which still resonate to this day,” he will say.
“We must find ways of healing, and to support each other to pursue solutions.
“I cannot say often enough that it is by coming together that we create the best chances to improve our world and the lives of people everywhere.”
Recent years have seen the Commonwealth beset by criticism over colonial-era injustices, and claims for reparations, including for slavery.
“The Commonwealth family is strongest when we are connected, through friendship,” the King will say.
“As I have said before, the Commonwealth is like the wiring of a house, and its people, our energy and our ideas are the current that runs through those wires.
“Together and individually, we are strengthened by sharing perspectives and experiences, and by offering and borrowing the myriad ways we have each tackled the challenges of our time.”