The paper £50 note is the last to be replaced by a polymer version, which is waterproof and harder to rip, making them last longer.
The two windows and two-colour foil make it more difficult to counterfeit.
Turing's £50 note joins the Winston Churchill £5 note, Jane Austen £10 note and JMW Turner £20 note.
How did Alan Turing’s work help during the Second World War?
ALAN Turing was asked to join the Government Codes and Cypher School, a code-breaking organisation which is now known as GCHQ.
The organisation moved to Bletchley Park in Buckinghamshire, which became the top secret home of Britain’s code breakers.
He was based in the famous Hut 8 and his most notable achievement at Bletchley was cracking the Germans' ‘Enigma’ code.
The Enigma was a machine used by the German armed forces to send encrypted messages securely.
Together with fellow code-breaker Gordon Welchman, developed a machine called the Bombe which from late 1940 was decoding all messages sent by the Enigma machines.
Turing’s team also cracked complex German naval signals in 1941, contributing to Allied victory in the Battle of the Atlantic.
His other work included developing a machine to encode and decode voice communications.
Paper versions can continue to be used until September 30 2022, when the old £20 notes will also finally be withdrawn from circulation too.
Shoppers will either need to spend them or deposit them into a bank before the cut off date or they risk losing the cash forever.
The Bank of England's Chief Cashier, Sarah John, said: "The polymer £50 note is the most secure Bank of England banknote yet, and the features of the note make it very difficult to counterfeit.
"All of our polymer banknotes can be checked by looking for two key security features: a hologram which changes image; and see-through windows. So, if you can check one denomination of banknote, you can check them all.
"The new £50 notes, like the polymer £10 and £20 notes, contain a tactile feature to help vision impaired people identify the denomination."
Turing is best known for being the Enigma code breaker at Bletchley Park responsible for decrypting Nazi messages – shortening the war by four years.
Benedict Cumberbatch played the troubled scientist in the 2014 film, The Imitation Game.
Despite his monumental help with the national effort in the Second World War, he was charged over homosexual activity in 1952.
He pleaded for chemical castration by a series of injections of female hormones, which made him impotent. He was also barred from continuing his work with GCHQ.
Turing died from cyanide poisoning in an apparent suicide in 1954, and 59 years later the mathematician was granted a posthumous royal pardon in 2013.
The new note features a photo of him taken in 1951 by Elliott & Fry, alongside a table of a mathematical formula.
Underneath the picture of Mr Turing is a quote from him, saying: "This is only a foretaste of what is to come, and only the shadow of what is going to be."
The Bank of England Museum has also launched an online exhibition to coincide with the Turing £50 banknote entering circulation.
To celebrate the launch, Snapchat has created filter to teach Brits more about the mathematician, by holding their phone up to the £50 note or a picture of it.
Ahead of the launch, the Bank teased fans with a cryptic binary code message in a nod to Turing.
When a release date was announced, spooks at GCHQ published their toughest ever puzzle to honour the former code-breaker.
The number of people paying by cash has fallen sharply during the coronavirus pandemic after several stores encouraged contactless payments instead.
The number of cash payments made last year plunged by 35%, according to recent figures released by trade association UK Finance.
Coins and banknotes were used for 17% of all payments in the UK last year, while 27% of payments were contactless.