Gruen joins from Weber Shandwick, where she was an associate director. She will join the Milk & Honey board, and is tasked with developing the agency's B2B proposition and leading on insights and innovation.
"I have loved my time at Weber Shandwick and playing senior roles in both large agencies and in-house," she said. "I'm eager to bring my background of creative campaigning to [Milk & Honey] and continue the impressive growth trajectory."
Gruen is one of four new recruits to the agency this month. Lewis Oakley has joined as client manager from Red Havas, where he worked on large consumer brands. Milk & Honey has also appointed client assistant Lizzie Elkin and executive assistant Petrina Marks.
"With every new hire we try to bring in new skills. Caroline's creative yet analytical mindset is going to be a huge asset to the leadership team," managing partner Kirsty Leighton said. "I am incredibly proud of what we have achieved in our first three years and look forward to continued growth."