Nichols will be responsible for "driving operational efficiencies" across the whole group following a period in which the business has grown through M&A.
He joins from Aon, where he was responsible for overseeing the insurance company’s change portfolio for the UK health and benefits business. He also shaped some of the larger change programmes for Aon across EMEA and globally.
Previously, Nichols held senior change and IT programme roles at Deutsche Bank and HSBC.
Instinctif Partners CEO Tim Linacre said: "I am delighted to welcome David to the Instinctif Partners team and his wealth of experience in transforming operations will help to shape and further enhance the business going forward."
The appointment follows a period of change at Instinctif, including new ownership and a restructured leadership team.
In September, the private equity arm of Lloyds Banking Group, LDC, replaced Vitruvian Partners as the PR agency's principle backer, which led to Linacre's role changed from group MD to CEO.
Nick Woods, who leads the financial services team, became the company’s youngest managing partner, and Melanie Toyne-Sewell was promoted to managing partner within the firm’s life sciences team.
A year ago, former CEO Richard Nichols moved to deputy chairman after Linacre's promotion to group MD.