Dedeker recently retired from P&G after spending 29 years in a variety of senior roles, most recently as vice-president of consumer and market knowledge external capability.
Prior to that she served as vice-president of global consumer and market knowledge for seven years.
In her new role, based in the Cincinnati office, Dedeker will report to Kantar CEO Eric Salama.
She will focus on leading Kantar's global initiatives with respect to research quality and industry transformation, and help shape the company's offer and go-to-market strategy based on an understanding of clients' existing and future needs.
Dedeker will also have direct oversight of US based Kantar HQ staff functions including Kantar client, business development and privacy roles.
Salama said: "In the industry debate around 'change or more of the same', I'm firmly in the camp of needing to change.
"We do great and wonderful things but we need to do them more consistently for all clients everywhere.
"I've long admired Kim's vision and the way that she and colleagues at P&G have led the industry in so many ways.
"I'm thrilled that she is joining us and believe that we can harness her passion, leadership around data quality issues and desire to increase the value that agencies add to their clients to help Kantar achieve its goal."
Dedeker said: "I've said in many forums that this is a pivotal time for our industry and that transformation is imperative.
"In my view, Kantar is proving itself to be a role model for the collaborative spirit and commitment required. I have great respect for the capabilities and talent at Kantar."