Snedden will be responsible for leading Wunderman's data practice, working primarily on its Jaguar business.
During her time at Tangible Data, Snedden oversaw a client list that included British Gas, Nationwide Building Society and Energy Savings Trust.
She has also spent time working as a consultancy director at EHS Discovery, and as a brand manager at GlaxoSmithKline.
Meanwhile Wunderman has also appointed Nick Fletcher as head of account planning.
Fletcher joins the agency from Enfatico, where he held the role of EMEA head of planning.
He has also been a planning director at Wnek Gosper and a planner at BMP, where he worked on the agency's iconic Hamlet business.
In his new role, Fletcher will also be responsible for leading the strategy on Wunderman's Jaguar and Microsoft accounts.
The new appointments come just two weeks after Wunderman was awarded two high-profile projects from Cancer Research UK.
Brendan Tansey, the chief executive of Wunderman, said: "Nick and Janet form the two bookends of the Wunderman proposition of accountable creativity."