The highest-paid director at Dentsu Aegis Network earned £11.1m, including £5.3m in "compensation for loss of office", last year.
The operation’s annual accounts, which were filed at Companies House in the UK, do not identify the director.
It is thought to be Jerry Buhlmann, who stepped down as global chief executive and director on 31 December 2018 and is now an advisor to Japanese parent company Dentsu Inc.
A spokesman for Dentsu Aegis Network declined to comment.
The highest-paid director’s £11.1m package comprised £2.8m in basic remuneration, £2.7m as part of a long-term incentive scheme and £300,000 in pension contributions, as well as the £5.3m pay-off.
Individual pay packages for other directors were not disclosed in the accounts.
Dentsu Inc published its annual global results, including for Dentsu Aegis Network, its operation outside Japan, earlier this year.
Dentsu Aegis Network has filed international accounts in the UK because it has its headquarters in London.
The accounts said organic revenue rose 4.4% last year compared with 1% in 2017. Global headcount jumped 4.7% to 41,600 by the end of 2018.
Buhlmann spent 29 years at the company, starting as co-founder of BBJ Media, which later became part of Aegis.
He went on to sell to Dentsu for £3.2bn in 2012 and lead the combined business, Dentsu Aegis Network, which has doubled in size since then.
Tim Andree, the long-serving executive chairman, added the role of chief executive to his remit in January after Buhlmann’s exit.