He replaces Fred Joseph, who has been promoted to the new role of global chief digital officer for the Publicis network ZenithOptimedia.
Bertozzi, a former head of digital at ZenithOptimedia and commercial director of Zed Media, is returning to Publicis after a two-year stint as the director of advertising at TMP Worldwide, the recruitment ad company.
VivaKi's Nerve Center aims to develop new technologies for Publicis agencies.
VivaKi was created by Publicis in 2008 and one of its stated goals, alongside achieving greater buying scale, is to develop ways of working with online media owners and social networks.
Last month, Nick Burcher, another former Zed Media director, joined VivaKi Nerve Center as its head of social media and audience messages, EMEA.