A curable silicone composition comprising: (A) (A1) an organopolysiloxane having at least two alkenyl groups in a molecule and free of silicon-bonded hydroxyl groups or silicon-bonded hydrogen atoms, or a mixture of said component (A1) and (A2) a branched chain organopolysiloxane represented by an average unit formula; (B) an organopolysiloxane having at least two silicon-bonded hydrogen atoms in a molecule; (C) a diorganodialkoxysilane represented by a general formula; (D) a straight chain organosiloxane oligomer having at least one silicon-bonded hydroxyl group in a molecule and free of silicon-bonded hydrogen atoms; and (E) a hydrosilylation catalyst, can form a cured product which exhibits excellent initial adhesive properties and transparency and exhibits excellent adhesive durability and retention of transparency under conditions of high temperature and high humidity.