Sambrook will be the agency's first chief content officer and will be in charge of assisting clients to produce written, video and audio content.
He will report to Edelman EMEA president and CEO David Brain and will sit on the global executive committee chaired by Richard Edelman.
Global CEO and president Richard Edelman said: 'Richard's journalism and senior media company management resume is difficult to rival; equally important to us and our clients, Richard has been at the forefront of the digitisation of news and its interaction with the audience and stakeholders.'
Sambrook will work from the London office.
Ian Monk, a former journalist who established PR firm Ian Monk Associates said: 'Structural changes reverberating throughout the media industry have created an Armageddon in terms of journalistic redundancies. Many turn to what they are inclined to see as an entitlement to a lucrative career in PR.'
He adds: 'PR and journalism can be complementary professions but the requirements for success in each are often widely at variance with the other.
'Our industry should welcome a vibrant influx of journalists. But in the interests of professional respect and a proper estimation of its worth, PR needs to address the issues of proper mentoring and training requirements for the new intake.'