Deloitte is expected to be appointed as GSK’s auditor with effect from the accounting year ending 31 December 2018, following shareholders’ approval at GSK's annual general meeting in 2018.
The pharmaceutical company said the appointment followed a competitive audit tender process overseen by an executive steering committee of its audit and risk committee, chaired by Judy Lewent.
PwC, which has audited the company since GSK's inception in 2001, will continue to work with the firm until the end of next year.
Lewent, chairman of GSK's audit and risk committee, said, "I am pleased that having conducted a, thorough, open and transparent process, the audit and risk committee has concluded the audit tender.
“We would like to thank PwC for their significant contribution as GSK's auditor since the formation of GSK in 2001 and look forward to working with Deloitte in the future."
Under new EU audit rules, companies are required to put their audit out to tender every 10 years, and change auditor at least every 20 years.
The changes aim to increase competition between firms of different sizes, but within the FTSE 100, most have swapped among the Big Four.
Even though a large number of businesses (61%) said in April this year they were planning to invite tenders from at least one non-Big Four firm, of 25 audit tenders completed by FTSE 350 companies, none were awarded to a non-Big Four firm.
Last week, KPMG replaced PwC as the auditors of Legal & General after three decades with the same accountancy firm, and Rolls-Royce hired PwC after 26 years with KPMG.