Endemol UK head of corporate comms and PR Charlie Gardner insisted the appointment was purely to support Endemol's four-strong press office and had no bearing on the flotation. The listing was announced by Cesar Alierta, chairman of Endemol owner Telefonica, last month.
However, Gardner would not rule out the use of Brunswick for financial PR.
The move comes just over two weeks after Endemol and Brunswick denied they had been in talks or that the agency would handle financial or corporate comms.
In March, Endemol Holding corporate comms manager Jonni Abbenhuis said it would not appoint Brunswick 'in any capacity'.
RDF Media drafted in Finsbury for its £60m AIM listing earlier this month while Shed Productions engaged Financial Dynamics for its AIM flotation last month.
Observers have estimated that Endemol's flotation would give it a market value of £1.75bn, making it the largest of a series of TV production companies that have gone to market in the past few months. Others include Shed Productions, the company behind TV show Footballers' Wives.