Simon Law, the planning director at Goodby Silverstein & Partners in San Francisco, is joining the agency next week, while Giselle Okin has been appointed from United London, where she was the head of planning.
Law and Okin will sit alongside eight other planning directors and will report to Herve Hannequin, WCRS's head of planning.
Their appointment comes a week after the departure of WCRS's group strategy director, Cameron Saunders, who has left to head marketing at E4, More4 and FilmFour.
Law and Okin will split some of his responsibilities. Law will oversee the agency's 3 and 118 118 accounts and Okin will take on a number of accounts, including Bulldog.
At Goodby Silverstein, Law oversaw the agency's global HP business. Before this, he was a senior planner at Saatchi & Saatchi.
Okin has spent the past five years at United working on accounts such as Sky and Birds Eye. Before that, she was a senior planner at Bartle Bogle Hegarty for five years.
Will Orr, the WCRS managing director, said: "Simon and Giselle are two of the most sought-after planners in London."