Herein, we report the synthesis of novel thiazo-isoindolinedione derivatives in excellent yields (up to 92%) from the reaction of thiazolidinedione and isoindoline-dione. The structures of the novel compounds were elucidated by 1H-, 13C-NMR, and MS analyses. Furthermore, molecular docking analysis was performed to study the potential inhibition of the SARS-CoV-2 main protease (Mpro) by the new thiazo-isoindolinediones. The present study revealed that the new thiazo-isoindolinediones could inhibit the Mpro and represent a promising platform for the experimental development of new antiviral drugs based on thiazo-isoindolinedione scaffolds.