OMG said Choi is leaving the agency to pursue personal interests. Her final day in the role is slated for 1 November.
Choi is one of the founding members of OMD in the region. She ran OMD Greater China before being given the OMD Asia-Pacific remit in 2008.
"I am proud to have been associated with and to have contributed to the success of such a strong brand as OMD and have enjoyed every moment in the past 13 years," said Choi. "In particular, I’m delighted with the creative culture in our network which saw us creating innovative, brilliant and effective communication ideas for our clients while having our brand recognised as the most creative agency network. I will miss the countless colleagues I have worked closely with for so long and wish them and the company every success."
Choi began her career with Universal McCann in 1983, later developing a solid foundation in media at JWT. Prior to OMD, she played an important role in the launch of what is now ZenithOptimedia in Hong Kong.
OMG Asia-Pacific CEO Barry Cupples said he would immediately be adding OMD regional responsibilities to his current role.
"Maggie was one of the founders of OMD Hong Kong before taking on the role for Greater China and then on a broader regional basis," Cupples added. "Over these years she has made countless contributions to our organisation. We will miss her wisdom, her terrific strategic skills, as well as the team building skills that helped make OMD what it is today."