The joint venture will be known as iProspect China and Aegis will integrate all of the performance marketing capabilities of Adsit into its existing iProspect network.
Adsit will provide access to its e-commerce platform, its data pool, and key people,
enabling iProspect China to become a fully integrated, digital performance marketing agency.
Services will include search, display performance and ecommerce specialisation, in order to service the fastest-growing sector of marketing in China, as well as the existing Aegis Media client base.
Cindy Xue, chief operating officer of Adsit, will be appointed to chief executive of iProspect China.
Nick Waters, chief executive of Aegis Media Asia Pacific, said: "The combination of scale in both search and digital performance marketing will place iProspect China in a strong position and well ahead of our peer group of multinational competitors, who have not yet addressed the explosive growth of ecommerce in the market."
Last week, Aegis signed a "definitive agreement" to acquire a full-service Chinese digital media and marketing agency, Catch Stone, for an initial consideration of RMB 550m (£55.2m).
Aegis is itself in the process of being sold to Japanese giant Dentsu for £3.2bn, subject to shareholder agreement next month, but plans to continue its acquisition strategy.
Separately, rival holding company WPP has also been on the acquisition trail, today (24 July|) announcing its WPP Digital arm has acquired a majority stake in KKLD, a leading German-based digital agency.
Yesterday, WPP Digital acquired a majority stake in Acceleration, a marketing technology solutions group with offices Buenos Aires, Cape Town, Dubai, Johannesburg, London and New York.Follow @nickbatten2