Activity throughout June will advertise its mobile offer and Streetmap promotion, offering free map downloads to mobiles.
It forms part of a 拢10 million brand refresh, of which the web makes up about 10 per cent, marking an "increased investment in online" for O2, said head of advertising Tom Sutton.
He added: "Online is a great media to generate two-way dialogue. As a business, we have recognised the digital revolution and have quite a dominant share of voice in online media."
The web push was created by Agency Republic. The brand refresh launched on last month.