The agency, which already represents malt whisky Balvenie and Italian beer Peroni Nastro Azzuro, won the account following a three-way pitch.
Seventy Seven’s remit includes generating global comms platforms and ideas for the whisky brand, as well as delivering a global press office service.
The global brief will support Grant’s key markets including the UK, USA, Portugal and France and new markets including Poland, Romania, Russia and Latin American.
Owned by William Grant & Sons, the family-owned distiller, Grant's whisky is now distilled by the fifth generation of the founder’s family using the same techniques it first employed in its production over 120 years ago.
The Seventy Seven team will report to Grant’s marketing manager, Jeanette Edwards, and global brand comms manager, William Grant & Sons, Quyen Ha.