Fused pyrazoles and 2,5-disubstituted thiazolinone derivatives are attractive molecules for drug design development that are widely recognized as significant biological activity exhibition scaffolds. A considerable number of them were utilized as anti-cancer medications. In this current study, hybrid molecules that exhibited kinase inhibitory activity in addition to anti-tumor properties were synthesized. Our plan was to create a series of disubstituted-1,3-thiazolinone on fused pyrazolo[3,4-d]-thiazole derivatives as efficient anti-cancer drugs with low cytotoxicity and significant biological availability properties using 2-hydroxy acetophenone thiosemicarbazene and ethyl chloroacetate to provide 2-[2-(2-hydroxy phenyl)ethylidene)hydrazinyl]-1,3-thiazole-(5H)-one (3) as the essential precursor to heterocyclization processes. Compounds (3-8) were prepared and identified using infrared, 1H, and 13C-NMR spectral data. These synthesized compounds were evaluated for their in vitro cytotoxic activity against the two cancer cell lines (MCF-7 breast cancer and HepG2 liver cancer). The preliminary screening of their compounds for their anti-cancer activity revealed that compound (6) possessed the highest anti-cancer activity. It's interesting to note that these substances, when compared to the reference medicines Erlotinib and Lapatinib, respectively, significantly caused apoptosis in the HepG2 and MCF-7 cell lines using flow cytometry analysis, suggesting potentially high therapeutic ratios.