We describe a biomimetic organocatalytic enantioselective decarboxylative addition of malonic acid half thioesters to imines. This simple protocol makes use of readily available Cinchona‐derived organocatalysts and nucleophiles at the carboxylate oxidation state. The resulting β‐amino thioesters, being attractive precursors for the preparation of optically active β‐amino acids, are formed in good yields and in up to 79 % ee. As suggested by several mechanistic insights the desired products are formed via initial formation of a thioester acetate enolate via decarboxylation of the malonic acid half thioester, followed by addition to the imine.