The 18 new thiazolo[4,5-b]pyridin-2-one derivatives have been synthesized using alkylation, cyanethylation, hydrolysis, and acylation reactions. The structures of the obtained compounds have been confirmed by 1H NMR spectroscopy, mass spectrometry, and elemental analysis. The study of the in vivo anti-inflammatory activity of the synthesized substances was assessed by using the functional model of carrageenan-induced rat paw edema. The present results of anti-inflammatory activity have shown that the synthesized compounds demonstrated considerable anti-inflammatory effects. Some of them approach or exceed the comparative drug Ibuprofen in terms of activity.