Johns replaces head of corporate media relations Mike Haines, who quit the FMCG giant after 23 years.
Haines is considering his next career move, but said he will not retire.
Johns’s arrival comes at the end of the company’s five-year ‘Path to Growth Strategy’ and as foods director Patrick Cescau prepares to succeed Niall FitzGerald as chairman in September.
Johns reports to head of corporate relations Mandy Cormack.
Before BT, Johns held top comms positions at Homebase and Sainsbury’s.