Aberrant activation of NLRP3 inflammasome is present in a subset of acute and chronic inflammatory diseases. The NLRP3 inflammasome has been recognized as an attractive therapeutic target for developing novel and specific anti-inflammatory inhibitors. Cellular structure-activity relationship-guided optimization resulted in the identification of 4-oxo-2-thioxo-thiazolidinone derivative 9 as a selective and direct small-molecule inhibitor of NLRP3 with IC<sub>50</sub> of 2.4 μM, possessing favorable ex vivo and in vivo pharmacokinetic properties. Compound 9 may represent a lead for the development of anti-inflammatory therapeutics for treating NLRP3-driven diseases.