Production of high-performance polyesters with tailored degradability remains a challenge. Here, a series of poly(ethylene-co-isosorbide terephthalate) (PEIT) copolyesters were synthesized by varying the isosorbide (IS) content (0-20 mol %) using tetrabutyl titanate (TBT) as the catalyst. By variation of the IS content, the thermal, mechanical, and optical properties of the copolyesters were effectively tailored. As the IS content increased, the T_g was raised from 80 to 101 °C, and the tensile strength from 58.8 to 68.7 MPa. Moreover, excellent transparency was maintained (up to 90% light transmittance). Interestingly, the susceptibility to hydrolytic degradation was significantly enhanced by the incorporation of IS, with PEIT-20 showing approximately 3.5 times higher weight loss compared to PET after 50 days of alkaline degradation in 0.1 M NaOH solution. This outlines an attractive approach for developing high-performance copolyesters with tunable properties and degradation rates, suitable for applications in transparent thermal packaging materials.