The synthesis, characterization and methyl methacrylate polymerization behaviors of 2‐(N‐arylimino)pyrrolide nickel complexes are described. The nickel complex [NN]2Ni (1, [NN] = [2‐C(H)NAr‐5‐tBu‐C4H2N]−, Ar = 2,6‐iPr2C6H3) was prepared in good yield by the reaction of [NN]Li with trans‐[Ni(Cl)(Ph)(PPh3)2] in THF. Reaction of [NN]Li with NiBr2(DME) yielded the nickel bromide [NN]Ni(Br)[NNH] (2). Complexes 1 and 2 were characterized by 1H NMR and IR spectroscopy and elemental analysis, and by X‐ray single crystal analysis. Both complexes, upon activation with methylaluminoxane, are highly active for the polymerization of methyl methacrylate to give high molecular weight polymethylmethacrylate with narrow molecular distributions. Copyright © 2009 John Wiley & Sons, Ltd.