A simple and cost‐efficient nickel catalytic system for the annulation of 2‐haloaldimines with alkynes to synthesize 3,4‐disubstituted and 3‐substituted isoquinolines at room temperature has been developed. The air‐stable and inexpensive Ni(dppe)Cl2 was employed as a precatalyst, and Et3N was found to be an essential additive for obtaining high yields. By using this nickel catalytic system one‐pot three‐component direct synthesis of isoquinolines starting with simple 2‐halobenzaldehydes, tert‐butylamine, and alkynes were also achieved. These reactions occur in moderate to excellent yields with complete regioselectivity. Moreover, these reactions feature a broad substrate scope, easy scalability, operational simplicity, and excellent practicality.