The two latest London sites on the A41 Hendon Way and at Purley Way Fiveways will be unveiled today with launch advertisers Sky, Ikea and Audi all appearing.
The Hendon Way site is next to an arterial junction, which connects London's commuter belt with the A41 and the Brent Cross shopping centre slip road, while the digital Purley Way Fiveways sight is on the route from Gatwick to London, and is close to the Valley Park retail hub.
Jonathan Lewis, managing director at Outdoor Plus, said: "We're continuing to add to our network, giving brands access to the best sites in and around London, allowing them to tap into upmarket commuters, as well as people working in the heart of London."
Barry Louth, head of media planning at Sky, said: "Our 'Summer of Sport' campaign is designed to attract new customers. The site at Purley Way Fiveways is one of the highlights across the plan and the location injects premium quality as well helping us reach a broad audience."
In April, Outdoor Plus also introduced a digital site in East London, on the A12 Cross Route.