A thermally conductive silicone composition of the invention comprises: (A) an organopolysiloxane having a viscosity of at least 500 mPa·s at 25° C.; (B) a thermally conductive filler; (C) a fine silica powder; (D) an organopolysiloxane having a hydrolyzable group and having a viscosity of less than 500 mPa·s at 25° C.; and (E) a silane compound containing a hydrolyzable group. The composition possesses excellent handleability and workability at low viscosity and which, after application onto surfaces, is not subject to slipping-off when this surface assumes a vertically position, even under harsh temperature conditions.