A large see-through window with a blue and gold foil is printed on the front of the note, depicting the Turner Contemporary gallery in Margate, England, designed by architect David Chipperfield and the Margate lighthouse.
The new design will be issued on 20 February 2020, and has been billed as the most secure banknote yet.
As Britain's most common, and most forged, banknote, the new £20 note will incorporate extra security features including two windows and a two-colour foil, making it harder to counterfeit.
The shape of the note's large window is based on the design of the fountains in London's Trafalgar Square.
The smaller see-through window in the bottom corner of the note takes cues from Tintern Abbey in Wales, which was also the subject of one of Turner's well-known works.
The new note was launched last week at the Turner Contemporary as a nod to the 18th-century artist who the gallery is named after, and whose self-portrait is featured on the reverse.
Turner is the first artist to feature on a British banknote.
"Our banknotes celebrate the UK's heritage, salute its culture, and testify to the achievements of its most notable individuals," said Bank of England governor Mark Carney.
"Turner's contribution to art extends well beyond his favourite stretch of shoreline. Turner's painting was transformative, his influence spanned lifetimes, and his legacy endures today," he continued.
The new £20 note is a continuation of the Bank's move from paper to polymer notes, which are designed to last longer, stay in better condition, and are harder to forge.
The £20 will join the polymer £5 and £10, which are printed with the portraits of Winston Churchill and Jane Austen, with a £50 note featuring early computer scientist Alan Turing set to follow in 2021.
Like the polymer £10, the £20 will also include a tactile feature to help people with visual impairments to identify the value.
The new note also features Turner's signature from his will, and a quote from an 1818 lecture by the artist that refers to the innovative use of light, shade and colour in his works: "Light is therefore colour."
Like all notes, it will include a portrait of the Queen, which is printed on the window with "£20 Bank of England" printed twice around the edge, and a metallic hologram that changes between the word "Twenty" and "Pounds" when it is tilted.
The Central Bank of Norway also recently updated its 50 and 500 kroner notes, which feature pixelated images of Norwegian coastlines designed by architecture studio Snøhetta.
They are the first Norwegian notes to not have portraits of people as the main design. On the reverse side of each note are traditional images of fish, sailing vessels and waves.