Facebook already has ad sales deals with MSN elsewhere in the world, but this is the first time the partnership has extended to Asia. Previously advertisers wishing to buy its inventory had to use a self-service mechanism or go via a sales team in California.
MSN is working with online sales house Pixel Media to help attract the interest of marketers.
The MSN tie-up will be expanded to further markets in the region, with India expected to be next. Separate sales arrangements already exist for Japan and Australia.
Facebook is now the most popular social network in Hong Kong. In a recent Hitwise report, it had a 37.7% share of visits, ahead of Xanga on 33.6%.