De Groose, the former managing director of Naked Communications, has not yet revealed her next career move.
The agency network is poised to announce a successor "shortly", while EMEA chief executive Giulio Malegori will work with De Groose and the UK and Ireland leadership team to ensure a smooth transition.
De Groose said: "After eight wonderful years at Dentsu Aegis, I have decided that now is the right time to step down. I have loved every moment of working with this incredibly talented team of people and I am extremely proud of everything that we have achieved.
“I’d like to thank all the team at Dentsu Aegis for their support, energy and dedication to our clients over the last four years. I am confident they will continue to grow and succeed under new leadership and wish them well.”
Malegori added: “Tracy has been a great asset for our UK business which has been growing both organically and via strategic and relevant acquisitions. More importantly Tracy has built a very strong leadership team in the UK.
"I would like to thank Tracy for her valuable contributions and delivery during her years at Dentsu Aegis Network and I wish her all the best for the future.”
Previously the UK chief executive of Carat, De Groose has been one of the key industry figures leading the charge for diversity. She is an executive member of Wacl and volunteers as a Marketing Academy mentor, while internally she oversaw the launch of the network’s Women & Leadership Programme, Gender Equality Network, LGBT+ Network and Fortysix, a digital agency that will be entirely staffed by young people from diverse backgrounds.
Speaking to Daniele Fiandaca in The Drum’s Token Man series earlier this year, De Groose said: “At different points in your life and stages of your career, you are given the opportunity to be brave. Sometimes those points are obvious, others take reflection to recognise. Sometimes it takes someone else to point out your bravery.
“We are told that men are twice as likely to take risks as women, but everyone has the capacity to be brave. If our future leaders, both men and women, were inspired to be just 5% braver in their choices and decisions, just how amazing would that be?”