Chris Rumfitt will join Edelman in March, taking the role of director and reporting to Edelman's public affairs MD Alex Bigg.
Rumfitt is understood to have been in talks with agencies since PRWeek revealed his resignation after five years at Network Rail (PRWeek, 11 January).
As head of external affairs, he led a 70-strong comms team, spanning public affairs, media and community relations. Previously, he worked for Weber Shandwick.
Network Rail is yet to appoint a replacement.