Catalytic oxidation of hydrosilanes constitutes a green and sustainable alternative to the conventional hydrolysis of chloro- and alkoxy-silanes for the preparation of diverse silanols. However, several limitations still exist with this approach regarding the limited substrate scope, prerequisite uses of excess amounts of strong oxidants and/or precious transition-metal catalysts, and unsatisfactory product selectivity. Herein, we reported our development of a highly selective and scalable dehydrogenative hydroxylation of hydrosilanes, featuring a low loading of the Earth-abundant cobalt catalyst, water as the green oxidant, and good generality for organohydrosilanes, hydrosiloxanes, and even poly(hydrosiloxane).