The 68-year-old broke the record of Queen's Victoria's oldest son Albert, who went on to become King Edward VII after holding the title of Prince of Wales for more than 59 years before becoming monarch.
Charles, who turns 69 in November, is already the oldest heir apparent.
However, as Albert — known in the family as Bertie — was made Prince of Wales when he was barely a month old, while Prince Charles was not given the title until July 1958, when he was nine, it has taken until now for him to overtake his great-great-grandfather.
The milestone today came a day after his wife, Camilla — Duchess of Cornwall, named a Royal Navy aircraft carrier after her husband at the ceremony at Rosyth Dockyard, Fife, in Scotland.
"I name this ship Prince of Wales. May God bless her and all who sail in her," she said at the ceremony involving the traditional break of a whisky bottle.
The 65,000-ton carrier, the seventh in the British Navy to be named after the Prince of Wales, is due to start sea trials in 2019.
Clarence House in London is the official residence of the Prince of Wales, but in 2006 his Duchy of Cornwall bought Llwynywermod, a Welsh home for the prince.
The estate near Myddfai, Llandovery in Carmarthenshire, is used by Prince Charles for meetings, receptions and concerts, and as the base for his several yearly visits to Wales, including the annual week of summer engagements, known as Wales Week.
Prince Charles is the 21st Prince of Wales in the current line. Albert Edward was created Prince of Wales on December 8, 1841 when he was just one-month-old.
He acceded to the throne as Edward VII on 22 Jan 1901, meaning he served as Prince of Wales for 59 years, one month and 14 day.
Prince Charles was created Prince of Wales when he was nine years old on July 26, 1958.
He has now held the title for 59 years, one month and 15 days.
The Prince of Wales is historically the title bestowed upon the heir to Britain's throne.
Stay informed on all the latest news, real-time breaking news updates, and follow all the important headlines in india news and world News on Zee News.