Speaking at Mansion House, where he attended a glittering white-tie dinner with Queen Camilla to recognise the work of City of London civic institutions and Livery Companies, the King urged the public to rise above "rancour and acrimony" during online debates.
He said: "The instinct to co-operate wherever and whenever possible is deep within us.
"Even in the most fractious times – when disagreements are polished, paraded and asserted – there is in our land a kind of muscle memory that it does not have to be like this; that the temptation to turn ourselves into a shouting or recriminatory society must be resisted ... especially in the digital sphere, where civilised debate too often gives way to rancour and acrimony."
The King continued: "These instincts come together in perhaps the deepest of all our reservoirs: the one that irrigates our crucial sense of responsibility, both individual and collective, that enables us to fulfil our duties as good citizens who understand, without having to write down or formalise them, the decencies on which our institutions and our constitution depend, as well as our relationships."
Speaking of writing things down, Charles had a little fun at his own expense, recalling his famous mishap with a fountain pen that was caught on camera just days into his reign in September 2022. Take a look below...
It comes just a week after the Duke and Duchess of Sussex urged social media companies to reduce the amount of harmful content children can see online to protect their mental health.
Harry and Meghan appeared at a mental health awareness festival run by non-profit Project Healthy Minds in New York on 10 October.
Speaking on the panel co-ordinated by the couple's Archewell Foundation, father-of-two Harr urged tech bosses to "stop sending children content you wouldn’t want your own children to see".
Meghan said she and her husband are focusing on what they can do behind the scenes to make social media use "safer, better and more positive" and that the couple have spoken to tech executives about the issue.
She added: "People are getting hurt – and people, specifically children, are dying.
"A year ago we met some of the families, not all of them. At that time, it was impossible to not be in tears as I’m sure so many of you have been today hearing these stories.
"As parents, our kids are really young – they’re two-and-a-half and four-and-a-half – but social media is not going away.
"I think by design, there is an entry point that is supposed to be positive, in creating community and something has devolved, and there is no way to hear that and not try to help these families have their stories be heard."
Harry has been advocating for change on social media platforms for years, and in an opinion piece for Fast Company in 2020, he wrote: "It shouldn’t be seen as a coincidence that the rise of social media has been matched by a rise in division amongst us globally.
"Social media’s own algorithms and recommendation tools can drive people down paths towards radicalism and extremism that they might not have taken otherwise."
Listen to HELLO!'s A Right Royal Podcast and find out which royal residence Queen Camilla refused to enter in the early days