PwC's 27-year contract with global household products company Unilever has come to an end as the company awarded the £14.5m contract - the 8th largest in the country - to KPMG.
PwC also earned £1.6m in audit-related fees and a further £810k in non-audit fees.
Unilever's shareholders decided at the May AGM to reappoint PwC for 2013 audit, and to then put the audit out to tender for the next year's accounts.
The last time that Unilever put its external audit out to tender was in 2002.
A spokesman for the company said that the need to be at the forefront of good governance influenced the decision.
Byron Grote, chairman of Unilever's audit committee, thanked PwC for its services over the time, and said he looked forward to working with KPMG, whose hire is subject to shareholder approval at next year's AGM.