The contract, which was awarded after a competitive pitch, means Clear Channel will install more than 100 digital screens in Westfield's six shopping centres outside of London, including Birmingham, Derby and Belfast.
Separately, Clear Channel has extended its contract with Meadowhall to install new digital screens in the Sheffield-based shopping centre. Together with Westfield, this will increase Clear Channel's digital offer by 60 per cent by the first quarter of 2012.
JCDecaux previously handled the outdoor ad sales for Westfield's regional shopping centres. CBS Outdoor has the ad sales contract for Westfield London and Westfield Stratford City.
Bill Giouroukos, the director of operations at Westfield UK, said: "We have moved our strategy to all-digital."