The ring-opening polymerization of two caprolactone monomers catalyzed by zinc undecylenate (ZU) is reported. Polymerizations were performed in bulk with benzyl alcohol (BnOH) as an initiator at 90 and 110 °C, respectively. A slower polymerization rate was observed for γ-octyloxy-ε-caprolactone as compared to ε-caprolactone. Diblock copolymers were synthesized by the sequential monomer addition at 90 and 110 °C. The kinetic studies performed for the ring-opening polymerization of ε-caprolactone and γ-octyloxy-ε-caprolactone and the successful synthesis of diblock copolymers by the sequential monomer addition confirmed the controlled/living nature of zinc undecylenate catalyzed reactions.