A straightforward enzymatic single-step route toward the synthesis of alpha,omega-functionalized polypentadecalactone (PPDL) macromonomers containing dithiol, thiol-acrylate, diacrylate, or dimethacrylate end groups has been developed. Two solvent-free approaches, mixing all components at start, using Candida antarctica lipase B (CALB) as an efficient catalyst were demonstrated. In the first approach difunctionalized polymers (with dithiol or thiol-acrylate end groups) were synthesized by mixing lipase, lactone, and equimolar amounts of functional initiator (6-mercapto-1-hexanol) and terminator (11-mercapto-1-undecanoic acid or vinyl acrylate). Polymers with a high fraction (95%) of dithiol end groups or polymers with thiol-acrylate end groups (86% and 96%, respectively) were obtained. In the second approach, a functional diester (ethylene glycol diacrylate or ethylene glycol dimethacrylate) was mixed with lactone and lipase without predrying, using water as an initial initiator. Reduced pressure was applied after 2 h of incubation to evaporate water and push the equilibrium toward high functionalization. Polymers with >96% diacrylated or dimethacrylated end groups were achieved.