He will manage the day-to-day operations of the W&K network, reporting to president Dave Luhr, who was himself chief operating officer until 2013.
Christie assumes the role on 1 April, the agency’s 35th birthday, and will continue to be based in London.
W&K London deputy managing director Helen Andrews will succeed Christie. Andrews joined the agency in 2008 and was promoted from head of account handling to deputy managing director in 2014.
Christie has led the London shop as managing director since 2004. He joined from Euro RSCG (now Havas), where he was marketing director.
Luhr said: "[Neil] knows great creative work and is never afraid to push for it internally or with clients. This relentless drive has powered W&K London to become globally recognised for great work and strong results for clients."