Pending approval at the society’s 2019 AGM, EY will be appointed for the period commencing 5 April 2019.
PwC was paid almost £9m in fees by Nationwide over the past two years.
Kevin Parry, chairman of the Nationwide audit committee said, "The tender process was transparent, comprehensive and thorough. We look forward to working with EY in the future."
Omar Ali, EY UK financial services managing partner, added that the firm was “honoured” to win the contract.
Nationwide said it will work together with PwC and EY to ensure a smooth transition process.