The agency was informed of the Stella parent InBev's decision on Monday, putting an end to a three-month pitch process, which began when the incumbent, Lowe, resigned the account in August.
Mother will now produce a campaign that will run in 2009 across the beer brand's global markets.
Sources close to the pitch suggest it was a closely fought contest, with both Mother and Publicis' pitch work going through an extensive global research phase over the past three weeks. It is understood that Mother pitched a more humorous approach to the brief, which will undergo further development before going into production next year.
A spokeswoman for InBev said: "The work done by Mother on the 4% launch campaign and on the pitch convinced us of their great creative capability and their ability to help us grow Stella Artois globally."