A series of nicotinic acid benzylidene hydrazide derivatives (1–18) was synthesized and tested in vitro for biological evaluations. The antimycobacterial activity results indicated that the presence of electron-withdrawing halogen groups at para position of the phenyl ring improved their activity. The results of antiviral evaluation depicted that none of the synthesized derivatives inhibited the replication of viruses at subtoxic concentration. Further, the antimicrobial screening results indicated that compounds having OCH3 and NO2 substituents were the most active ones. QSAR investigations revealed that multitarget QSAR models were effective in describing the antimicrobial activity.