The Prince of Wales says he will stop talking about matters he feels strongly when he becomes a king, as he is not "not so stupid."
He has been campaigning for issues like the environment for decades, but says he will not do the same with the monarch.
Speaking in a BBC documentary to mark his 70th birthday, Prince Charles said the idea of continuing to intervene was "nonsense."
He said it should work within "constitutional parameters".
She has campaigned on issues such as the environment, wildlife conservation, architecture and the use of GM crops.
Totally different & # 39;
In the hourly program, he was asked about what some of his people were calling for, but said he always tried to remain a "non-political party".
He said: "I think it is important to remember that there is only room for a sovereign at a time, not two.
"So you can not be the same as the ruler if you are the Prince of Wales or the heir.
"But the idea, in a way, that I will continue in exactly the same way, if I have to succeed, is complete nonsense because the two – the two situations – are completely different."
Asked if his public campaign would continue, he said: "No, he will not, I'm not that stupid.
"I realize that this is a separate exercise that is dominant, so of course I fully understand how it should work."
Documentary filmmaker John Bridcut, who followed the basilica for 12 months, said Prince Charles "jumped a little" on the use of the word mixing and instead preferred to think of his interventions as "motivation."
The heir of the throne said: "If you are mixing to worry about inner cities as I did 40 years ago, then if that's mixed I'm proud of that."
By Nikolai Vichsel, royal correspondent
He has spent his adult life trying, as he puts it, "to make the difference." Often this has led the Prince of Wales to talk about issues for which he feels deep: environment, GM crops, central cities, architecture, education, homeopathic medicine and others.
Prince Charles is accused of "mixing". It has, in some cases, provoked irritation to the government departments, which had to respond to the honest letters of the "black spider" who were always, politely but often persistently, an issue that comes to the prince's attention.
All of them have caused more concern. Prince Charles fully appreciates that when he succeeds his mother and becomes king of Britain, should these interventions be stopped?
Those who know him have for years declared that he understands that there is a line which, as a master, could not pass.
They have said that he particularly understands that, as a king, he has to stop his "campaign".
Prince Charles himself has ceased to say so public. He has said that any reference to how he would act as a monarch could be regarded as disrespect for his mother.
However, with the Queen now in her 93th year and with Prince Charles to celebrate her 70th birthday, she has declared – publicly and explicitly – that she admits that her interventions in public debate should stop as soon as she becomes a king.
"You're working," he says in the BBC documentary, "within the constitutional parameters."
It is reasonable to assume that his assurances will be heard with some relief in Whitehall and the corridors of power.
Mr Bridcut said: "People who think they hang, longing to be king, are very wrong.
"It is not something that dies to assume, because it will inevitably arise only after the death of his mother."
He added that Cornwall's Duchess, who also interviewed in the documentary, "argues that this weight is not too heavy on his shoulders."
The BBC has gained exclusive access to Prince Charles film, which is on November 14th.
Also featured in the program, the Cambridge duke said he would want his father to spend more time with his grandchildren – Prince George, Princess Charlotte and Prince Louis.
Prince William said, "when he is there, he is brilliant," but "we need him as much as possible."
"People at His Side"
By Roger Harrabin, BBC Environmental Analyst
The prince warned decades ago of climate change caused by man. It was controversial for some time, but there is now scientific consensus on the threat.
About wildlife, he rightly predicted huge loss of species. Campaign against the destruction of tropical forests and will be pleased with the recent focus on the impact of agriculture on forests and therefore on climate.
His worry about the soil sounded thorny to some observers, but now it is recognized that many areas face a crisis of land degradation and loss.
On these issues, the dominant flow towards the future monarch.
As far as GM crops are concerned, the prince remains in conflict with the scientific institute.
In other hobby horses, such as homeopathy and architecture, expressed opinion rather than fact – but will have some people at his side.
- Prince, son and heir: Charles At 70, will be screened at BBC One on Thursday 8 November at 21:00.