A phosphoric acid-catalyzed regio- and enantioselective N²-propargylation of pyridazinones has been achieved, providing chiral N²-alkylated pyridazinones in moderate to good yields (up to 93%) with good enantioselectivities (up to 96% ee). Moreover, the chemo- and enantioselective N-alkylation of 2-pyridones (up to 88% yield, 96% ee) has also been realized by slightly modifying the reaction conditions.