The 75-year-old’s condition’s is benign but he will have the corrective procedure at an unnamed hospital next week.
All public engagements have been postposted for a short period.
The announcement comes on the same day it was revealed that the Princess of Wales was in hospital after undergoing abdominal surgery.
In a statement, Buckingham Palace said: “In common with thousands of men each year, The King has sought treatment for an enlarged prostate.
“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.”
Benign prostate enlargement is common in men aged over 50. It is not a cancer and usually does not pose a serious threat to health, the NHS states.
Symptoms include a difficulty emptying the bladder. It is usually diagnosed by a GP running tests, while treatment takes place depending how severe the symptoms are.
King Charles was due to attend a series of meetings and events at Dumfries House tomorrow and Friday.
Meanwhile, Kate Middleton will spend up to two weeks in hospital after undergoing successful abdominal surgery. The 42-year-old was admitted to The London Clinic on Tuesday for the planned procedure.
The princess is likely to spend between two and three months recuperating and is not expected to return to public duties until after Easter .
This is a breaking story – updates to follow