Havas Media has looked after Nando’s since 2011 when MPG Media Contacts won the account, which was said to be worth £2m at the time.
Industry observers offered varying estimates for the current value of the account but it is thought the peri-peri chicken restaurant chain could spend as much as £5m in the UK.
Accounts for Nando’s Group Holdings, which reported a 14% rise in worldwide turnover to £848m last year, say that developing a "global, defined, unique and distinctive brand" is a strategic priority.
Nando’s has rolled out a new visual identity, featuring a cockerel, that "pays homage to our Southern African roots" to improve its "brand strength.
Nando’s trades in a dozen markets, including its flagship UK operation.
"Each market has a brand plan focused on delivering consistent and aligned messaging, and international brand health is now measured across all our key markets and our major franchise markets once a year on a consistently executed international health brand tracker," the accounts said.
Nando’s UK press office did not respond to an inquiry about its media agency arrangements in time for publication.
Essence and Havas Media would not comment.
Media Sense, which advised on the review, also would not comment.
WPP announced plans to turn Essence from a digital agency into a full-service media agency in June 2017 as part of a restructuring.
Essence picked up BT as its most significant UK client from now defunct sister WPP agency Maxus in November but it took five months of discussions.
Nando’s has used a number of different UK agencies, including AnalogFolk for digital and Adjust Your Set for content marketing, in recent years.