The catalytic activity of chitosan (Cs) and grafted Cs led to the preparation of terephthalohydrazide Cs Schiff’s base hydrogel (TCsSB), which was then investigated as an eco-friendly biocatalyst for synthesizing novel thiazole derivatives. TCsSB exhibited greater surface area and higher thermal stability compared to Cs, making it a promising eco-friendly biocatalyst. We synthesized two novel series of thiazoles via the reaction of 2-(2-oxo-1,2-diphenylethylidene) hydrazine-1-carbothioamide with various hydrazonoyl chlorides and 2-bromo-1-arylethan-1-ones, employing ultrasonic irradiation and using TCsSB as a catalyst. A comparative study between Cs and TCsSB revealed higher yields than TCsSB. The methodology offered advantages such as mild reaction conditions, quick reaction times, and high yields. TCsSB could be reused multiple times without a significant loss of potency. The chemical structures of the newly synthesized compounds were verified through IR, 1H NMR, 13C NMR, and MS analyses. Six synthesized compounds were assessed for their in vitro antibacterial effectiveness by establishing the minimum inhibitory concentration against four distinct bacterial strains. The docking analyses revealed favorable binding scores against several amino acids within the selected protein (PDB Code-1MBT) for these compounds, with compound 4c exhibiting particularly noteworthy binding properties. Additionally, the in silico ADME parameter estimation for all compounds indicated favorable pharmacological properties for these compounds.