Hawker has launched the business having originally sold his crisis communications agency, Partner PR, to Financial Dynamics nine years ago.
He then stayed with Financial Dynamics through its sale to FTI Consulting in 2006, playing a pivotal role for the agency and becoming its issues, crisis and litigation senior managing director.
Slate Campaigns will specialise in what Hawker calls "critical campaigning" with a focus on litigation communications, crisis communications, political campaigning and issues management.
Declining to disclose current clients but revealing they included a government and an industry association, he said:
"The idea behind Slate Campaigns is that, in this increasingly digital age, reputation management requires specific and focused campaigning activity to promote an organisation and to protect it from having its reputation wiped away by critics with an agenda.
"The PR industry’s traditional approach to crisis communications no longer works. A new form of pragmatic but robust advocacy is required that allows clients to wipe the slate clean and to protect themselves from being slated. This is what Slate Campaigns will deliver."
He added: "I am looking forward to greater involvement in two areas of particular personal interest – taking on banks that have let down customers, and companies that take a blasé approach to consumers’ right to privacy."
Hawker will be part of a three-strong team at the consultancy, in what one corporate agency head described as a "massive loss" to FTI.
A spokesman for FTI, which is not actively seeking a replacement for Hawker, said: "We will continue to work with Jonathan on a case-by-case basis."