The pair will deploy their own separate radio equipment in 23 large cities, covering roughly 2,500 sites, or 16% of combined mast sites, as well as in London, which was covered by an agreement last year.
“Greater autonomy in major cities will allow us to accelerate deployment, and together with active network sharing, ensures that our customers will get super-fast 5G in even more places more quickly, using fewer masts,” said Vodafone’s UK chief executive Nick Jeffery.
Vodafone switched on its 5G network for both consumers and business customers in seven cities on 3 July.
Cornerstone, the 50:50 joint venture company that owns and manages the pair’s mobile towers, will be used in the deployment of both networks and look to capture further operational efficiencies.
Vodafone, which in May slashed its dividend 40% in order to provide some "financial headroom" as it looks to fund the roll-out of 5G, the €18.4bn acquisition from Liberty Global and cut debt, and O2 said they will also proceed to “explore potential monetisation options” for Cornerstone.
Jeffrey said the agreement means the pair can boost capacity where customers need it most.
O2, which is owned by Spain’s Telefonica, said the agreement is a “very effective” use of the mobile spectrum acquired in the last auction.