The appointment by the organisation, which oversees $180.5bn of assets globally, follows a competitive pitch involving around half a dozen agencies.
CNC is to handle corporate and financial comms from its hubs in London and Hong Kong, with additional on-the-ground support across Europe and Asia.
Toronto-based OTPP had worked with Bell Pottinger since 2013; the agency was placed in administration in September this year following the crisis over its controversial activities in South Africa.
In the UK, OTPP is part of a consortium that owns London City Airport.
Deborah Allan, MD, communications and media relations at OTPP, said: "We were very impressed by CNC’s insight-driven approach, creative thinking and deep understanding of corporate and financial communications, and their appreciation of our global presence and relationships. We are looking forward to getting the partnership started immediately."
In April, CNC owner Publicis announced plans to merge the agency with Sweden-based sister shop JKL, in a move to further align the holding company’s operations. The new group will operate under a single P&L, with a combined global team of around 200 people and 13 offices in nine countries.