Compared with the widely explored exo-selective C-H cyclization, transition metal-catalyzed endo-selective C-H cyclization of benzimidazoles with alkenes has been a formidable challenge. Previous efforts mainly rely on substrate-controlled methods, rendering the product complexity restricted. Herein we report a catalyst-controlled method to facilitate endo-cyclization, in which a bulky N-heterocyclic carbene ligand and tBuOK base-enabled Ni-Al bimetallic catalyst prove critical to the endo selectivity.