Weisinger will work across Dare, Elvis, EDC's design agency Identica and the PR unit Citizen.
She will start her new position in April and report to Gregor Angus, the president of EDC Europe. Her role will cover the UK primarily, but will also include Europe.
Weisinger most recently worked at McCann London as its chief marketing officer. Before that, she was the marketing director at Fallon for just under seven years.
Earlier in her career, she was an account supervisor at Saatchi & Saatchi New York, moving to DLKW in 1998 to become its new-business director.
She then moved to TBWA, where she was the marketing director for two years, before joining Fallon in 2004.
Angus said: "We have big ambitions and Helen joining our team will be of tremendous value."