Polymer banknotes, which can be recycled when they are taken out of circulation, have been introduced to replace the tradtional paper version.
The New Fiver, featuring Sir Winston Churchill, is the first to be released. It is around 15% smaller than the paper £5 note.
The Bank of England has printed 440 million £5 notes ready for issue and they will begin to be available from many cash machines and bank counters today.
The public can continue to spend paper £5 notes as usual until 5 May 2017 after which they will cease to be legal tender.
Officials said the notes are cleaner, safer and stronger, with better security features to make it harder to counterfeit.
The note is resistant to dirt and moisture and remains in better condition for longer, officials said.
Mark Carney, the Governor of the BoE, said: “The New Fiver commemorates one of the greatest statesmen of all time, Winston Churchill, who remarked that ‘a nation that forgets its past has no future’. Banknotes are repositories of the United Kingdom’s collective memory, and we will be reminded of Churchill’s enormous contributions as he once again becomes part of our daily lives as the New Fiver flows out into tills and pockets.
“While the use of polymer means it can better withstand being repeatedly folded into wallets or scrunched up inside pockets and can also survive a spin in the washing machine. We expect polymer notes to last at least two-and-a-half times longer than the current generation of fivers and therefore reduce future costs of production.”
Paper £5 notes will be gradually withdrawn from circulation as they are banked by retailers and businesses.
Following this, paper £5 notes will still be exchanged at the Bank of England. The new polymer £10 featuring Jane Austen will enter circulation in summer 2017 followed by the J.M.W. Turner £20 note by 2020.