Last year, the king, an outspoken campaigner on environmental issues and supporter of a sustainable economy, launched the 'Coronation Food Project', his mission to 'bridge the gap between food waste and food need'.
On Thursday, the monarch will open the initiative's first two food hubs - distribution centres which are designed to save and circulate tonnes of surplus food.
He will visit one of the hubs in south London which will host a ‘surplus food festival’ making meals created from food which would have gone to waste, as well as virtually opening the other site in northern England.
Their aim is to make it easier for food charities such as FareShare and the Felix Project to provide support for those in need, Buckingham palace said.
It said since the launch of the scheme, the project had helped save an additional 940 tonnes of surplus food which was to the equivalent of more than 2.2 million meal portions.
Charles' birthday will also be marked in a more traditional manner with gun salutes at the Tower of London and in the capital's parks.
The celebrations come in a busy week for the monarch which included him attending the London film premiere of "Gladiator II" on Wednesday night.
His wife Camilla was forced to miss the event as she recovers from a chest infection. Official engagements for the monarch himself are still being carefully monitored by his medical team as he continues his treatment for cancer.
