The US food giant has briefed the agency to assist with lobbying and corporate affairs in the UK.
The agency will aim to manage comms around corporate integration, and reassure the combined company's employees, shareholders and other stakeholders. It will also assist with lobbying of decision-makers in Westminster and Whitehall and seek to repair any damage done to the US firm's reputation in the UK media.
Blue Rubicon has previously handled reputation management for Cadbury. It will now work alongside Mandate, which was recently brought to handle public affairs on a retained basis, and Brunswick, which will continue to handle all financial PR for the firm.
Kraft was criticised by the Takeover Panel earlier this year after it reneged on a promise to keep open a Cadbury factory in Bristol. It will now close by 2012 with the loss of 400 jobs, transferring much of its work to Poland.
Finsbury was contracted by Cadbury to help manage the PR bid to fight off a takeover.
At the time, Cadbury chairman Roger Carr urged shareholders not to let Kraft 'steal' the British confectionery group after the US food group's £10.5bn hostile offer. However, a fresh bid of £11.5bn a week later saw the Cadbury board perform a U-turn and back the bid. In May, the US company said it would move staff from its Cheltenham office to Cadbury's current headquarters in Uxbridge, Middlesex, and Cadbury offices in Bournville, Birmingham.
The Kraft account is being led by Blue Rubicon directors Sam Shorten and Rosie Steel.
Jonathan Horrell, director of corporate affairs UK & Ireland, Kraft Foods said: 'Everyone knows Kenco, Philadelphia, Terry's Chocolate Orange, Dairylea and Oreo, but fewer people know the real Kraft Foods, even though we have been in the UK for 85 years. It's a good time to tell our corporate story to a wider audience.'
Brunswick declined to comment.