Provided is a curable polyorganosiloxane composition which advantageously forms a cured product suitable for LED or optical lens, wherein the cured product has excellent light transmission properties in a short wavelength region, i.e., in the blue to ultraviolet region and is unlikely to suffer yellowing due to exposure to heat.A curable polyorganosiloxane composition comprising: (A) alkenyl group-containing polyorganosiloxane which comprises (A1) branched polyorganosiloxane comprising an SiO4/2 unit and an R3SiO1/2 unit, and optionally an R2SiO unit and/or an RSiO3/2 unit (wherein each R independently represents an unsubstituted or substituted monovalent hydrocarbon group), wherein at least three R per molecule are alkenyl groups, and optionally (A2) linear polyorganosiloxane having R bonded to a silicon atom (wherein R is as defined above), wherein at least two R per molecule are alkenyl groups, wherein 90 mol % or more of the R present in components (A1) and (A2), excluding alkenyl groups, are methyl groups; (B) polyalkylhydrogensiloxane comprising an SiO4/2 unit and an R3(CH3)2SiO1/2 unit (wherein each R3 independently represents a hydrogen atom or a methyl group), wherein at least three R3 per molecule are hydrogen atoms; and (C) a platinum group metal compound.