Until Senecal leaves at the end of the year, Sollenberg will temporarily be co-global chief executive, but going forward will oversee all of the agency’s offices around he world, based at CP&B's headquarters in Boulder, Colorado.
He joins from Forsman & Bodenfors, where he has been chief executive for the last 14 years. The Swedish agency is known for creating global ad campaigns for Ikea and Volvo (including 2013's "the epic split" starring Jean-Claude Van Damme) and has won over 100 Cannes Lions, including six Grands Prix.
MDC Partners, CP&B’s parent company, acquired Forsman & Bodenfors last year and formed a "strategic partnership" between the two agencies.
Chuck Porter, chairman of CP&B, said: "I’ve known Erik for a long time. We have the same beliefs and aspirations, and he has an uncanny understanding of what’s needed for a creative-driven enterprise to thrive.
"Lori Senecal is a great leader and she’s done a masterful job of architecting an innovative global strategy and structure for the agency. As she was making her decision to leave the industry, it was pretty clear what the best next step for the agency would be.
"I think Erik's leadership, together with the creative talent that’s already here, is going to lead to some pretty spectacular things."
Meanwhile, Forsman & Bodenfors has promoted its veteran creative Silla Levin to replace Sollenberg as chief executive.
Levin, who will start the new role on 1 September, has been with Forsman & Bodenfors as an art director for the last 16 years. Until the MDC acquisition, she held partner status at the agency.