Like chief executive Giles Hedger and chief creative officer Justin Tindall, Chicourel has taken up an offer of voluntary redundancy as the agency looks to cut headcount by about 11% after losing its NatWest ad account.
A statement from the agency said it had "reluctantly accepted" Chicourel’s request, wished her the best for the future and said a further announcement regarding restructuring and leadership would be made in mid-January.
Chicourel joined as CSO in March 2018 after four years at Saatchi & Saatchi, where she was most recently head of strategy.
She said she had taken voluntary redundancy "for two reasons: to protect the jobs of as many of my much-loved strategy gang as I could and to have a new beginning in a place where, alongside my new sisters and brothers, I will help reshape the future".
Along with Hedger and Tindall, M&C Saatchi co-founder and executive director Maurice Saatchi resigned on 10 December, along with all three non-executive directors: Michael Dobbs, Sir Michael Peat and Lorna Tilibian.
Reflecting on her time at the agency, Chicourel commented: "It was the best of times, it was the most challenging of times. There were many joyful moments: with Coca-Cola Premier League, Apprenticeships, Twinings, Tourism Australia.
"There was the sad loss of NatWest. There was the immense honour of being part of an extraordinary team of strategists (now my friends for life) and see them win much deserved awards this year. They made me laugh, they made me better, they made me proud every single day.
"Last thing I wanted to say is that my Christmas wish is for M&C Saatchi (and every agency that has shaped our industry) to rise from the difficult times affecting us all. I also wish for more camaraderie in our industry. No-one really wins when iconic agencies struggle."