Danny Mok has resigned as CEO of Grey Group in Hong Kong and Shanghai to take on the CMO role as CSL Limited.
From 16 September he will take charge of the 1O1O, One2Free and New World Mobility brands.
Mok has 20 years of experience across advertising, media and the telecommunication industries.
Phil Mottram, chief executive officer of CSL Limited, described Mok as a renowned business development and marketing expert in the region.
"I am looking forward to the level of energy and focus on customers that Danny will bring to us.
"Given his depth of experience and market knowledge, Danny will be driving the marketing team to achieve our strategic goals in one of the most competitive and fast-moving markets in the world."
"It is my great honor to be part of the CSL team led by Phil and to working with the team to develop the CSL brands further in the market. I'm impressed with his vision for the company," said Mr Danny Mok.
Mok also served as vice-chairman of the Association of Accredited Advertising Agencies of Hong Kong (HK4As).