The portrait will be the only change to existing designs of £5, £10, £20 and £50 notes and will start to enter circulation from mid-2024.
New notes will feature the King's portrait on the front and in the see-through security window.
Existing notes will still be accepted in shops after the new notes begin to circulate.
Queen Elizabeth was the first and only monarch to appear on circulating Bank of England banknotes, starting in 1960. Notes issued by Scottish and Northern Irish banks do not depict the monarch.
There are about 4.5 billion individual Bank of England notes worth about £80bn in circulation at present.
Coins carrying the image of the late Queen will still be accepted in shops, in the same way as banknotes.
For anyone taking part in a family Christmas quiz this year, it is worth remembering that, in ascending order, the reverse side of current polymer Bank of England banknotes feature Sir Winston Churchill, Jane Austen, JMW Turner and Alan Turing.
Cash use has become far less frequent when compared to debit cards, owing primarily to the use of contactless payments and then accelerated by the Covid pandemic. The buying power of specific coins and banknotes have also been diluted by rising prices.
However, there is still keen interest from consumers and collectors about the images used on cash.
Collectors will be particularly excited to get their hands on the lowest serial numbers of the new King Charles banknotes when they appear.