Leeds-based Poultner Partners will handle all PR for Evershed's offices in Newcastle, Leeds and Manchester, alongside work for the commercial practice group.
Republic, headquartered in London, has won the account covering London and East England offices, plus the corporate, property and e-strategy practice groups.
Corporate PR firm Key Communications - the only incumbent to remain on the roster - takes on a refocused brief overseeing Birmingham, Cardiff and the East Midlands.
Key, which has worked with Eversheds for seven years, also looks after the human resources, litigation, dispute management and commoditised services practice groups.
According to Eversheds marketing services director Andrew Harvey, the review was kicked off last autumn due to a group restructure, which saw the business organised by practice groups rather than regions.
The review initially concentrated on in-house comms, which last year saw some roles refocused.
Harvey said: 'As with many firms that grow over a period of time, we had a series of arrangements with agencies and sole practitioners and we wanted to deal with fewer people and make sure those we used knitted well with the in-house team.'
On the reasons for choosing the current roster, Eversheds PR manager Monica Keavey said: 'A three-agency model gives us the flexibility we need and the opportunity to share ideas, while retaining the value of specialised teams.'