The ultraviolet-curable organopolysiloxane composition comprises (A) a first organopolysiloxane having, in a molecule, at least one isopropenyloxysilyl-substituted ethyl or propyl group, (B) a second organopolysiloxane having, in a molecule, at least 2 silicon-bonded mercaptoalkyl groups, (C) an organosilicon compound having at leaast one vinyl group in a molecule and (D) a photosensitizer. The composition can be rapidly cured by exposure to ultraviolet light into a cured silicone rubber body without the problems and disadvantages in the conventional ultraviolet-curable silicone rubber compositions.