Castor oil and vernonia oil platforms were used to synthesize two linear and branched α,ω-diene monomers. ADMET copolymerization conducted in bulk yielded a series of copolyesters with various degrees of branching with respect to the feed ratio between the two α,ω-dienes. After hydrogenation, these copolyesters showed thermo-mechanical properties in accordance with the ones of LLDPE and VLDPE with tunable melting points between 50 °C and 90 °C. As expected, and similarly to the “PE-like” polyesters reported in the literature, the presence of ester functions distributed along the polyethylene backbone slightly lowered the crystalline ability of the so-formed polyesters. Nevertheless, these novel bio-based polyesters constitute a good sustainable alternative to olefin-based elastomers (LLDPE and VLDPE), especially for specific applications which require degradability.