King Charles 'grateful for kind wishes' as he leaves hospital after corrective procedure

King Charles III told supporters he's "grateful" for their "kind wishes" as he was discharged from hospital on Monday.

The 75-year-old monarch was admitted to the London Clinic – where the Princess of Wales also recently had abdominal surgery – on Friday for a "corrective procedure" for an enlarged prostate.

After three nights in hospital, he left on Monday afternoon (UK time), accompanied by Queen Camilla, waving to the crowds of well-wishers gathered outside.

Watch the video above.

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Buckingham Palace announced the news after the King left the clinic, near Regent Park, at 3pm local time.

"The King was this afternoon discharged from hospital following planned medical treatment and has rescheduled forthcoming public engagements to allow for a period of private recuperation," the palace statement read.

"He would like to thank the medical team and all those involved in supporting his hospital visit, and is grateful for all the kind messages he has received in recent days."

READ MORE: Camilla's 'unusual' move as Charles undergoes procedure

The monarch was discharged from hospital just hours after his daughter-in-law, the Princess of Wales.

Earlier on Monday (late on Monday AEST), Kensington Palace said Catherine had returned home, 13 days after she underwent planned abdominal surgery on January 16 for an undisclosed condition.

"The Prince and Princess wish to say a huge thank you to the entire team at The London Clinic, especially the dedicated nursing staff, for the care they have provided,'' the palace said.

Queen Camilla visited her husband several times during his hospital stay.

Reports suggest the monarch may take as long as a month to return to royal engagements the longest time he has been off duty since taking the throne.

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All the times the royals have been in hospital

The King decided to announce the surgery in advance in an effort to encourage other men to have their prostates checked in line with public health advice.

"In common with thousands of men each year, The King has sought treatment for an enlarged prostate," the statement released on January 17 said.

"His Majesty's condition is benign and he will attend hospital next week for a corrective procedure.

"The King's public engagements will be postponed for a short period of recuperation."

It is understood the King was examined after experiencing symptoms of an enlarged prostate. These can include difficulty urinating, as well as pain during urination.