It is not yet known which of Saatchis' Asian offices Billingsley will work out of, but he is expected to take on the role in the summer.
Spencer McHugh, the head of brand communications at Orange, will replace Billingsley as the new brand director.
The move, Billingsley's first agency-side, comes two years after he joined Orange from Nokia. His career also includes time at Unilever and Coca-Cola.
During his tenure at Orange, Billingsley has overseen the launch of the global "I am" campaign by Fallon and the appointment of WPP's Mediaedge:cia to its £76 million media planning and buying business.
Billingsley's departure follows that of Richard Wheeler, the head of music and film partnerships, who left for Virgin Media earlier this month.