Willey will work on an ad hoc, project-by-project basis, focusing initially on the agency's Specsavers account.
Willey, who has set up her own strategy and training consultancy, will also give advice to Hanover's healthcare media business, covering international and UK pharmaceutical brand public relations.
Willey has also written for the Daily Mail, The Sun, The Mirror, Sunday Mirror, Daily Star and News of the World.
She said: "The need to address the challenges facing the NHS, the role it looks set to play in the general election and the level of discovery and innovation in the sector make this a really exciting time for healthcare communications. I’m pleased to be joining Hanover’s team of sector experts to help clients communicate and get their message across in this changing and crowded environment."
Hanover’s global head of healthcare Andrew Harrison added: "Jo brings unparalleled insight in how to effectively deliver media stories and campaigns into the healthcare market. She makes an excellent addition to our expanding and expert healthcare communications team."