Nicole Lander joins the transport firm after two years at Dairy Crest. She previously held senior positions at high street retailers Tesco and Woolworths.
Lander replaces Nicola Marsden, who left National Express earlier this year after seven years to take the top PR role at defence and security firm QinetiQ (PRWeek, 7 February).
National Express has recently centralised its comms departments into a 25-strong team, which Lander will head up.
It includes financial, corporate, corporate responsibility, consumer, PA, internal comms and investor relations activity.
Lander's remit covers North America, Spain and the UK. She will report to National Express Group chief executive Ray O'Toole.
She said: 'The transport sector is highly competitive and is a big comms challenge. There will be meaty internal comms challenges because the company has become highly acquisitive.
'There will also be corporate responsibility work because of the focus on companies' environmental footprints as the Government promotes rail travel.'
Meanwhile Lander's departure sees a restructure at Dairy Crest. She will not be replaced but her role has been split into three.
Milk procurement director Arthur Reeves has been promoted to external comms director.
John O'Maoileoin, who was one of Tesco's three internal comms managers, joined as head of internal comms two months ago.
And Bill Haywood will oversee head of corporate responsibility.