The work is currently undertaken by in-house department Guardian Creative which comprises 48 staff. A Guardian spokesperson said it was too early to say whether jobs would go as a result of the move, but they said a voluntary redundancy scheme is ongoing which Guardian Creative staff have been invited to apply for.
Guardian Creative will continue to produce "promotional publications" in-house, including the award-winning pocket-size "Guides to" booklets.
GNM said in a statement that Guardian Creative will "retain editorial control of all commercial publications".
GNM director of consumer media Adam Freeman said in a statement: "Seven Squared Publishing is a large, well-established customer publisher, which produces publications of the highest quality. Partnering with Seven Squared will enhance Guardian Creative's existing editorial and creative output, providing a more flexible and responsive publishing service and give clients greater access to innovative content solutions. The move will also enable Guardian Creative to provide a more cost effective and variable business model to GNM, as part of our cost review."
Dominic Ponsford writes for Press Gazette.