She will lead programmes for key technology clients across EMEA.
Spitz, who will report to UK MD Fenella Grey, previously spent 15 years at agencies including Blue Rubicon and Lewis PR, leading UK and EMEA campaigns for clients such as Salesforce.com, Cisco and Experian.
Porter Novelli said: "Spitz has extensive corporate and B2B experience across the financial services, environment and energy, hospitality and retail industries, where she has advised on communications strategies and issues/crisis management."
Grey said: "Debbie brings a wealth of experience working with a wide range of impressive technology brands. Her background will serve us and our clients well as we build award-winning campaigns for our clients."
Spitz said: "I’m excited to join the talented team at Porter Novelli and contribute to the great work we’re doing for an impressive roster of technology companies. I believe deeply in Porter Novelli’s commitment to talent and outstanding client service, and am eager to put that into practice across the network."