Hagen will join Carat at the end of October from MPG Media Contacts, where he is a managing partner, strategy. Before that, he was the head of data at the Havas-owned agency for six years.
Reporting to Morris, Hagen will lead the restructured planning team. Carat recently dropped the distinction between digital and traditional planning in favour of a cross-platform approach.
The appointment will free Morris to concentrate on his broader agency role, working alongside the Carat managing director, Tracy De Groose.
De Groose said: "The appointment of Dan Hagen will future-proof our business; Dan is a huge asset in his digital brilliance, which has allowed him to navigate both offline and online planning."