The Monarch has taped a personal message regarding his experience with cancer, set to air as part of this year's Stand Up To Cancer initiative, spearheaded by a leading cancer charity and a major network.
The royal household confirmed the King would reflect on his "recovery journey" as a person living with the disease, in a recorded address on Friday evening at 8pm UK time.
The recording, taped inside his London residence a fortnight ago, will emphasise the vital significance of preventative health checks to help guarantee more people diagnose the illness at an initial point.
This will be a infrequent public commentary on the health of the King, who has been undergoing regular treatment since his condition was announced in early last year. But it is thought improbable the King will specify his specific form of cancer.
The awareness campaign each year collects money for scientific studies and patient care and urges people to get screenings to increase the odds of an prompt identification.
The King's candid approach about his health challenge, and managing the disease, has been intended to raise awareness and to get more people to get screened - and this will be escalated with this exceptional direct participation.
Up until now the King's primary strategy to his cancer has been to keep working, preserving a full diary despite his ongoing course of treatment, and he seems not to have sought to be defined by his condition.
The past twelve months has seen the King, 77, taking several foreign visits, notably to Italy and Canada, and welcoming the highest tally of official guests to the UK for almost 40 years, featuring the German president in recent days.
Friday evening's Stand Up to Cancer show on television, presented by well-known figures such as a team of famous hosts, will appeal to people not to be scared of getting cancer checks.
The hosts have been had experience with cancer - Davina McCall revealed last month she had had an operation for breast cancer, while Balding was diagnosed with the illness in the past. Host Hills has previously spoken about his father, who had a diagnosis and then later another illness.
The show will reach out to the approximate millions of people in the UK who charities says are not current with national health programmes, with an digital tool to let people see if they are able for examinations for key health indicators.
In an attempt to demystify cancer checks and show the value of timely identification there will be a direct feed from hospital departments at medical facilities in Cambridge.
"My aim is to reduce the stigma out of preventative tests and demonstrate the public that they are not isolated in this," commented a presenter.
At present in the UK, there are a number of national health screening services - for specific cancers - offered to eligible individuals.
A new scheme for lung health is also being slowly rolled out for individuals at potential risk of being diagnosed with the disease, focusing on people in a specific age bracket, who are smokers or have smoked in the past.
Individuals may enquire about prostate screenings, but there is lacking a standardised service operational.
The charity project, which has raised a significant sum over the past decade, is financing dozens of clinical trials encompassing 13,000 patients.
King Charles, in a message for guests at a gathering for support groups in April, had referred to acknowledging the "intimidating and at times scary reality" for patients and their loved ones.
But he noted his first-hand encounter of managing cancer had revealed that "the darkest moments of sickness can be alleviated by the support of carers," as he thanked those who supported cancer patients.
The Palace has not disclosed the specific type of cancer the King has, or the therapies he has undergone. The King's cancer was identified following he had received a medical treatment.