Livermore leaves his senior position at Saatchi & Saatchi Fallon (SSF Group), which he has held for ten months. He will take up the new role later this month.
Livermore said: ‘Applying the skills and techniques of successful political campaigns to give Blue Rubicon’s clients even more effective communication campaigns is an exciting prospect.’
Livermore was one of the first senior figures to leave Brown’s inner circle, departing in early 2008 after Brown attacted heavy criticism for pulling the plug on an early election.
Livermore had previously helped the Prime Minister to plan the strategy for the first 100 days of his premiership.
He also worked closely with Brown throughout his time as chancellor after being appointed a special adviser in 1998.
Blue Rubicon senior partner Fraser Hardie said: ‘Using extensive political campaign strategy and planning experience, Spencer will develop our strategic and planning capability taking it to a new level.'
Over the last year, Livermore has advised clients including Asda and Eurostar on brand strategy and competitive positioning. At the time of his appointment to SSF Group, Livermore was reported to have been in talks with Brunswick about a move into PR.
Blue Rubicon recently became the first agency to record three consecutive PR Week Consultancy of the Year titles.