In this study, phenyl-substituted derivatives with an isonicotinyl moiety were synthesized and evaluated for antimicrobial, antioxidant and antidiabetic activities. The derivatives were characterized using 1H and 13C NMR and FT-IR spectroscopy. Computational studies, including DFT calculations, FMOs, MEP, NBO, Fukui function, NCI and Topological analyses, were conducted to understand their chemical behavior. Molecular docking with LD Transpeptidase, Heme Oxygenase and PPAR Gamma was performed. The molecule 4H showed significant antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and Aspergillus flavus and a highest antioxidant activity with 92.03% DPPH radical scavenging at 120 μg/mL. Compounds 4H and 4Br exhibited notable α-amylase inhibitory activity. The findings highlight the therapeutic potential of these derivatives.