Diverse functional groups were introduced in isoquinolines under microwave‐assisted palladium‐ or copper‐catalyzed coupling reactions, which include functional groups to isoquinoline were achieved with 1‐substituted 4‐ and 7‐bromoisoquinolines, arylboronic acids, terminal alkenes, terminal alkynes, and azaheterocycles. 1,4‐ or 1,7‐Disubstituted isoquinolines were obtained in moderate to excellent yields within 1 h under microwave irradiation. The facile functional group modification of isoquinoline core could establish isoquinoline compound library for drug discovery.