He will head their risk management services division to mitigate risk for landlords and tenants worldwide.
The job will include evaluating how secure buildings are from terrorism, cyberattacks and traditional crime, and advising the firm on where they can safely buy property.
Kelly had numerous offers, including quite a few to head security at Wall Street banks.
"Commissioner Kelly could have chosen from a multitude of companies to work for and we are honored that he elected to join Cushman & Wakefield," said Cushman & Wakefield President & CEO Ed Forst. "His proven track record of successfully managing risk in business, law enforcement, public safety, and the military are obvious. The risks our global clients face are diverse, disruptive, geographic in scope, and constantly evolving. Adding one of the world's foremost risk management and security experts to our leadership team will provide our clients the highest level risk management service in the industry and adds incredible power to our brand."