Reporting directly to the partnership's chairman Charlie Mayfield, Moys will become director of communications heading a 20-strong team.
He joins from Cadbury, where he was global internal and interactive communications director during its controversial takeover by US food conglomerate Kraft Foods. He joined Cadbury in 2008, after five years at airport operator BAA where he headed internal comms.
He assumes overall responsibility for the partnership's media relations, public affairs and internal communications including its weekly magazine, The Gazette, and the John Lewis Partnership website.
Previous comms head Susan Donovan left the group at the end of January to take a career break abroad.
Helen Dickinson remains head of press and PR at John Lewis' retail business and Christine Watts continues as communications director for Waitrose, both reporting directly to the MDs of the brands.