It is understood that the king was 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.
About one in three men over the age of 50 will have some symptoms of an enlarged prostate, which is a gland that sits just below the bladder.
With guests including foreign dignitaries and members of the cabinet due to travel, Buckingham Palace felt it necessary to make people aware of the situation.
Benign prostate enlargement (BPE) is not cancer and it is not usually a serious threat to health, according to the NHS website.
With moderate to severe symptoms, medicine to reduce the size of the prostate and relax the bladder may be offered to the patient.