A series of novel N-(substitutedbenzylidene)-4-(1-((dimethylamino)methyl)-1H-benzimidazol-2-yl)thiazol-2-amine 5a-5o were designed and synthesized from o-phenylenediamine & lactic acid. All the synthesized compounds were characterized by FT-IR, 1H-NMR, Mass spectroscopy and bases of elemental analysis. In vitro M. tuberculosis method and agar streak dilution test were performed for screening antitubercular and antimicrobial activity, respectively. Results of biological studies revealed that all title compounds exhibited mild to good antitubercular and antibacterial activity. The relationship between the functional group variation and the biological activity of the screened compounds were discussed. The most active compound was found to be N-(4-Nitrobenzylidene)-4-(1-((dimethylamino)methyl)-1H-benzimidazol-2-yl)thiazol-2-amine 5b out of fifteen title compounds.