Roberts joined the AHDB in 2007 on secondment from the Meat & Livestock Commission, later signing a fixed-term contract to run until the end of 2010. At the NFU, he succeeds Richard Macdonald, who retires in late November.
An AHDB representative said: "Kevin was always on a fixed-term contract to see through the restructuring of the levy boards. We estimated everything would be complete by the end of 2010 but we have now reached a point of stability and time-wise it is good to look for a replacement CEO now."
NFU director of policy Martin Haworth will be taking up the post of acting director general on 26 November until Roberts starts.