Chiral amines bearing a stereocenter in the α position are ubiquitous compounds with many applications in the pharmaceutical and agrochemical sectors, as well as in catalysis. Catalytic asymmetric Mannich additions represent a valuable method to access such compounds in enantioenriched form. This work reports the first enantio‐ and diastereoselective addition of commercially available p‐toluenesulfonylmethyl isocyanide (TosMIC) to ketimines, affording 2‐imidazolines bearing two contiguous stereocenters, one of which is fully‐substituted, with high yields and excellent stereocontrol. The reaction, catalyzed by silver oxide and a dihydroquinine‐derived N,P‐ligand, is broad in scope, operationally simple, and scalable. Derivatization of the products provides enantioenriched vicinal diamines, precursors to NHC ligands and sp³‐rich heterocyclic scaffolds. Computations are used to understand catalysis and rationalize stereoselectivity.