A new series of 2,5-disubstituted tetrazoles and 1,2,3-selena/thiadiazolyl-2H-tetrazole derivatives were synthesized and evaluated for their in vitro antimicrobial and cytotoxic activities against pathogenic strains. The preliminary screening results indicated that some of the compounds demonstrated moderate to good antibacterial and antifungal activities, comparable to the first-line drugs. Compounds 6a and 6b exhibited pronounced cytotoxicity against Hep G2 and MCF-7 cell lines. The chemical structures of all the newly synthesized compounds were characterized by means of spectral and elemental analyses.