Open Road was handed the retained brief, previously estimated to be worth £10,000 a month, following a pitch involving the incumbent Portland.
One area of focus for the agency is thought to be the ongoing roll-out of Vodafone's recently launched 4G network as the company seeks to make up lost ground to competitors like EE, which started offering its own 4G service late last year.
The company is also battling on taxes, yesterday going on the front foot to tackle the issue over revelations it once again paid no corporation tax in the UK last year.
Publishing figures for the second time as part of a wider transparency drive, it yesterday claimed critics were showing a lack of understanding and called the UK market "one of the least profitable mobile markets anywhere in the world".
On the appointment of Open Road, a spokesman for Vodafone UK said: "Vodafone UK confirms that Open Road has been awarded the role of retained public affairs agency and will advise and support the in-house team in its dealings with political stakeholders. The decision followed a very competitive pitch involving a number of agencies."
PRWeek revealed last month that Vodafone UK's head of comms Christian Cull had lost his job following changes brought about by new CEO Jeroen Hoencamp.