Sutherland (pictured above) takes over leading Carat UK next month and will report to Matthew Platts, who was promoted to chief executive of Media Brands UK & Ireland last week.
She told Campaign that she plans to focus on "injecting more innovation, pace, and being mobile-first." She added: "It’s a solid business and I just want to make it brilliant."
Carat has 605 staff in the UK with clients including Adidas, Diageo, Kellogg’s, Mondelez and Santander.
Sutherland joined Fetch in 2016, and has worked at the network since 1999 in roles across Vizeum and Carat.
Hirst (above) joined Carat UK in July 2016 from fellow DAN creative shop Mcgarrybowen in a rare move for a creative shop leader head to switch to a media agency. The network is in the process of creating a new division and said it will announce further details about Hirst’s new role "in due course" so that he is able to "manage a smooth handover of his responsibilities".
Stef Calcraft, executive chairman at Dentsu Aegis Network UK & Ireland, said: "Jo brings a dynamic mobile-first philosophy to the heart of the business. She is a progressive leader with a collaborative style that inspires more innovative ideas and solutions for our clients, our people and our media partners.
"Jo has played a pivotal role in transforming Fetch into the thriving business that it is today and I look forward to her leading Carat through its next phase of growth.
"I’d like to take this opportunity to thank Rick for his dedication to Carat over the past two years. I am delighted that he remains within the group and wish him all the best in his exciting new role."