Selective hydrogenation of quinoline and its derivatives is an important means to produce corresponding 1,2,3,4‐tetrahydroquinolines for a wide spectrum of applications. A facile and efficient “laser irradiation in liquid” technique to liberate the inaccessible highly dispersed Co-Nx active sites confined inside N‐doped carbon nanotubes is demonstrated. The liberated Co-Nx sites possess generic catalytic activities toward selective hydrogenation of quinoline and its hydroxyl, methyl, and halogen substituted derivatives into corresponding 1,2,3,4‐tetrahydroquinolines with almost 100% conversion efficiency and selectivity. This laser irradiation treatment approach should be widely applicable to unlock the catalytic powers of inaccessible catalytic active sites confined by other materials.