OgilvyOne DNX won the business after pitching against two other agencies and will now handle all the digital work around EY’s "building a better working world" positioning.
Oystercatchers ran the pitch for the company, which rebranded from Ernst & Young in 2013. EY’s principal creative agency is Assembly, while media is handled by UM London.
Drew Nicholson, the chief executive of OgilvyOne DNX, said: "EY is a prestigious company with exciting ambitions for growth and a strong brand proposition."
John Rudaizky, EY’s global brand and external communications leader, added: "We chose OgilvyOne DNX because of their understanding of complex business markets and their ability to create and deliver powerful, emotive digital work."