O’Connor, who has spoken about holding republican views, debuted as Charles in series three of the Netflix show and will reprise the role in the forthcoming fourth series.
The 30-year-old said it was “just bizarre” that in order for Charles’ life to have meaning his mother must die.
Speaking to Esquire UK, he said: “For me, that’s the juicy stuff.
“The question of having to wait for your mum to die in order for your life to have meaning, and what that means for a young man. It’s just bizarre.
“Charles doesn’t necessarily want power, but until she dies, what the hell is he doing? What is his existence? He has no purpose.”
One scene in series three saw Charles tell Camilla Shand that his life was “not so much an existence as a predicament” because “until she (the Queen) dies I cannot be fully alive”.
Speaking about the upcoming series, which will introduce Diana, Princess of Wales, O’Connor told the magazine: “The Diana stuff has been thrilling to play.”
He also said his lack of knowledge about the royal family played to his advantage when it came to questions about his opinion of the Duke and Duchess of Sussex.
O’Connor said: “It’s quite useful, because if anyone tries to trick you into saying anything about the real royal family, I can’t, because I don’t know anything.
“When we went over to the Golden Globes, people were asking us about Harry and Meghan and I had to say, ‘I don’t know what you’re talking about’. Because I really don’t.”
Series three of The Crown also stars Olivia Colman as the Queen, Tobias Menzies as the Duke of Edinburgh and Helena Bonham Carter as Princess Margaret.
The September/October issue of Esquire UK is on sale now.