Harris will join FTI Consulting's global financial services division and provide strategic communications advice to clients.
FTI said his areas of expertise include issues management, executive positioning and employee engagement, and has provided senior counsel to C-suite executives.
At HSBC, Harris helped devise the bank's external affairs strategy, including a key role in its sustainability and climate-change communications. He has also been HSBC's head of comms for the Middle East and North Africa.
Harris has more than 20 years' experience, during which time he worked in senior comms roles at Goldman Sachs and Aviva, as well as spending five years at Tulchan.
Neil Doyle, a senior managing director and head of UK financial services in FTI's strategic communications segment said: "Paul has a proven ability to advise large institutions on complex, multi-stakeholder communications challenges at a time of significant change, and we're excited to welcome him to FTI Consulting."
Harris added: "I have worked closely with FTI Consulting for many years and have always been highly impressed with their breadth of understanding, depth of skill and considered judgement."
FTI has made several senior hires in recent months, including former Edelman healthcare MD Ann Bartling, former minister for culture, communications and creative industries Ed Vaizey and ex-Times senior journalist Tim Hames.
