Ducharme, who will work from the relocated London office, has been tasked with supporting UK business growth across the company's focus areas of building digital platforms, delivering integrated campaigns and content creation.
The move comes some 10 months after Sorrell kicked off his S4 Capital venture with the acquisition of the Dutch company.
She most recently worked as chief production officer at Publicis' Prodigious Worldwide. Prior to that, Ducharme was operations director at BBD Perfect Storm, which she joined from Quiet Storm, where she held the role of production director.
This isn't the first time Ducharme will work under Sorrell's leadership. From 2010 to 2014, she worked for WPP-owned Hogarth Worldwide as head of broadcast.
Discussing the new appointment, MediaMonks managing director, Martin Verdult commented: "We’re super keen to have Kieve on board. She has built an incredibly strong portfolio, achieving enviable growth for major brands and businesses – be it by crafting custom client solutions or developing new capabilities altogether."