Separately, PRWeek has learned that Tulchan managing partner David Shriver left the business earlier in the autumn after more than seven years at the company.
Wilson was press secretary at 10 Downing Street under Cameron between September 2013 and July 2016. Before that he spent two decades as a senior political journalist across a number of national newspapers including The Sun, The Daily Mail and The Daily Telegraph.
He will join Tulchan’s policy advisory practice when he starts at Tulchan on 1 December.
Andrew Grant, senior partner at Tulchan, said: "We have been successfully building our policy advisory practice over the past few years. Graeme's expertise and experience, particularly his many years in political journalism, will enhance our advisory capability and accelerate our continued growth in this increasingly important area."
Wilson said: "I am very pleased to be joining Tulchan, which has a well-earned reputation as a market-leading advisor on strategic corporate and financial communications. I'm looking forward to bringing my experience to Tulchan to ensure that it continues to offer the best possible advice to its clients."
Grant told PRWeek that the agency took a "collective decision" not to have the managing partner role, instead to give more responsibility to company partners; the agency hired six new partnerships in April this year.
Two partners, Ruth Royston and Basil Nicolaou, have now become management partners in the business.
Grant said the timing of Shriver's departure and Wilson's arrival are not connected.
Shriver joined the consultancy in 2009 from retailer Carrefour, where he was head of comms.
He told PRWeek: "I believe that intelligent, joined-up communications can have a transformative impact on a company's corporate reputation and I am planning to return to an in-house role where I can apply all that I have learnt over the last 13 years at Carrefour and Tulchan. I am in a number of conversations but no decisions yet."