Stewart has been with MTV for two years.
The resignation comes as company insiders cite other efforts by MTV Southeast Asia to reorganise its management framework. However, MTV denies any restructure plans.
Stewart joined MTV Asia-Pacific as its vice-president of research and planning in October of 2006 from Synovate's youth marketing research branch Filter Group. At the time, he reported to executive vice-president Chris Steward, who had rejoined the company after a stint away following the abrupt departure of Toby Hayward earlier that year.
Steward then left the company again in June 2007 and Stewart was promoted to senior vice-president of Viacom Brands Solutions International.