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."
It is understood that the King's meetings and events planned at Dumfries House on Thursday and Friday have been postponed on doctor's advice.
The monarch is understood to have been keen to share the details of his diagnosis to encourage other men who may be experiencing symptoms to get checked in line with public health advice.
Benign prostate enlargement, or BPE, is common in men aged over the age of 50 and is not usually a serious threat to health.
The condition does not mean the patient has an increased risk of developing prostate cancer.
The news on Wednesday afternoon comes less than two hours after it was announced the Princess of Wales was in hospital recovering from successful abdominal surgery.
It is likely that The Prince and Princess of Wales' planned trip to Rome later this year will be postponed, with no return to public duties likely before Easter, which falls at the end of March this year.
The palace has disclosed few details about the princess' condition and will not provide a running commentary but the length of time recovering both in hospital and then scheduled for at home indicate the surgery, while planned, was major.
The palace said that Kate wished to apologise for postponing her upcoming engagements.