Duncan, as managing director, will build Connect's London office in Clerkenwell, East London.
Connect, whose clients include Bentley and Bugatti, Birmingham Airport, Chiltern Railways and Tarmac, hopes Duncan will draw on his expertise in founding new agencies and innovating with digital media to widen the agency's reach and build its presence in the Capital.
In his most recent role at Spark44 he led the in-house agency as managing director and repositioned Jaguar as the "Alive' car brand.
Previous to founding Spark44, Duncan was chief executive of McCann’s network agency MRM Worldwide between 2005 and 2009. Duncan also founded the digital arm of Ammirati Puris Lintas and also Interpublic-backed Zentropy Partners.
His other digital innovations include launching interactive TV with the BBC in 1993, creating the first online car configurator for the Mini brand in 1997 and the first internet banking service for NatWest in 2003.
Duncan said: "Connect is growing at a rapid rate and has a strong heartland of combining creativity with technology to deliver exceptional results.
"My personal experience is in delivering projects that do just that, so I’m looking forward to helping the agency take the next step and move to the bigger international stage."
Duncan will also retain his involvement with Alternative Genius, a company for elite creative professionals to share their ideas. He said it is a "tremendously agile creative experimentation community that will add value in my new role".Follow @LouiseRidley