Pedersen will be based out of LBi IconNicholson's Manhattan office, where he will help direct and manage the integration of LBi's US operations.
He said: "It is an amazing opportunity that I join LBi US as its chief operating officer at this exciting time.
"I've been impressed with LBi's global work and award-winning capabilities. This is an excellent fit for my background, and I feel that I can add a lot of value as LBi grows its scope of services in the US market."
Pedersen led AKQA's retail practice, and was responsible for a number of strategic client relationships including BSkyB, Orange, Sainsbury's, Yell.com, HSBC and Intercontinental Hotels.
Luke Taylor, LBi group CEO, said: "We're honoured to welcome Frank Pedersen to LBi and our US operations. [His] demonstrated leadership will be key to our success in the US, providing ongoing direction of the company in the months and years to come."