The agencies involved in the final shortlist for the prestigious account, worth £30m, had been waiting on a decision since the account review began in December last year.
ZenithOptimedia will handle the planning and buying for television, press and radio and Meredian, its poster specialist, will handle outdoor activity.
Direct media will be controlled by Zed.
PHD previously handled strategic planning, the Allmond Partnership held the television brief and Outdoor Connection took care of O2’s outdoor activity.
ZenithOptimedia had previously handled O2’s press and radio buying.
Susie Moore, head of brand and marketing communications for O2 UK, said: “We have enjoyed great success with our advertising and media and all the incumbent agencies – PHD, Allmond Partnership and Outdoor Connection – have done a fantastic job for us. But, in order to ensure the best value and efficiency, we decided it was necessary to consolidate our media account.”
Gerry Boyle, managing director of ZenithOptimedia, said: “This was an excellent breakthrough for the agency. O2 is a fantastic brand.”