Foster, who was responsible for launching MPG’s data strategy department and worked with clients including bmi, Nationwide and EDF Energy, has 10 years’ experience at agencies, including roles at Tequila\London and Response One.
At TMW, she will head up the agency's data department, overseeing the data planning and analytics teams on accounts including Unilever, Diageo and Nissan. She will also be involved in driving new business.
Foster will report to chief operating officer Chris Freeland and director of strategy Kate Wheaton.
Freeland said: "After months of searching for the right person, I am delighted to welcome Anna to TMW. Her extensive knowledge and experience of all aspects of data make her the ideal candidate for this new role.
"With social media increasingly affecting the way we use and measure data, Anna joins us at an incredibly exciting time and we are confident that she will make a big impact on our clients’ business."
Foster said: "I am extremely passionate about generating insight from data and using it to deliver successful client campaigns.
"TMW’s constant ability to develop is what attracted me to this role and I am looking forward to working with the team to position data at the heart of everything the agency does and drive greater business intelligence for our clients."
TMW is this month celebrating 25 years of being in business.