A new approach to control the supramolecular organization of conjugated polymers is proposed, based on stereocomplex formation. It is illustrated by mixing polymer solutions of block copolymers, i.e., poly(3-hexylthiophene)-b-poly(L-lactide) and poly(3-hexylthiophene)-b-poly(D-lactide). The block copolymers were successfully synthesized via a three-step procedure including the use of metal-free organic catalysts in the ring-opening polymerization of L- and D-lactide. The thermal properties and microscopic morphology of sterecomplexed diblock copolymers show that the stereocomplexation of the polylactide blocks is able to prevent the crystallization of the regioregular poly(3-hexylthiophene) block into lone-range ordered parallel fibrillar structures. Stereocomplexation is also observed when mixing poly(D-lactide) homopolymer and poly(3-hexylthiophene)-b-poly(L-lactide) block copolymer.