Currently the executive creative director, Ang will report to Zayn Khan, the head of Ogilvy Malaysia.
Meanwhile, Alex Lee is stepping down as the agency's managing director after three years. He will remain within the Ogilvy network.
The new line-up is completed by Scott McBride, the managing director of the Glasgow-based digital marketing specialist OceanSeventy, who becomes general manager.
Ang, who retains her executive creative director role, will build relationships with senior clients, plan growth strategies and oversee talent development.