The new sites include four screens at London's Old Street Roundabout, the centre of the Old Street and Shoreditch area that is home to many technology start-ups and nicknamed the 'Silicon Roundabout'.
The first of 12 digital screens at the sites will go live at the end of October. London additions include two screens at Holland Park Tower in Kensington, one on the M4 London Gateway and two on the A40.
Two new sites are planned in the north of England, and one in London, but details have not yet been announced.
JCDecaux will also digitise two of its existing roadside sites with two screens each. Both faces of the M4 Tower will host digital screens, and two more will be installed at The Trafford Arch in Manchester.
The changes add 16 premium digital roadside screens to JCDecaux's current total of 14.
Spencer Berwin, the managing director of sales at JCDecaux, said: "This major new digital investment is bringing unprecedented flexibility and scale to the UK market.
"By 2014, JCDecaux will offer clients a portfolio of 30 digital roadside locations across the UK, in addition to an expanded rail and mall portfolio that will include 15 M-Vision screens in malls, 24 Transvision screens in stations, 800 D6s, and over 2,000 airport digital locations, including the exciting new portfolio at Heathrow Terminal 2."
As well as its main roadside screens, JCDecaux also operates 19 digital screens in London through its PrimeTime network, a series of LED screens the size of a 48-sheet.