Novel bio-based rubber-like materials are prepared from the oxidative copolymerization of tannin oleate esters and vegetable oils. The copolymer materials are prepared as solvent-cast films. Analysis reveals the reactivity and amount of vegetable oil employed has the greatest influence on copolymer crosslinking and mechanical properties. Copolymer film stiffness values range between 6 and 300 MPa and crosslink densities are 661–15 800 mol · m−3. Glass transition temperature (Tg) and Soxhlet insolubles (>80%) are relatively similar when forming copolymers with tung oil. In contrast, both Tg and degree of crosslinking decrease significantly with use of linseed stand oil. Thermogravimetric analysis indicates that the copolymers are thermally stable up to 200 °C.