3-(3,4-Dichlorophenyl)-5-(1H-indol-5-yl)-1,2,4-oxadiazole was synthesized via the condensation of 3,4-dichlorobenzamidoxime and methyl 1H-indole-5-carboxylate using superbasic medium (NaOH/DMSO). The compound was tested as a potential inhibitor of human monoamine oxidase (MAO) A and B. It demonstrated notable inhibition with an IC50 value of 0.036 μM for MAO-B and isoform specificity. The product was characterized by 1H NMR, 13C NMR, and HRMS. In conclusion, the new active MAO-B inhibitor may serve as a candidate for the future discovery of therapeutic agents for neurodegenerative disorders such as Parkinson’s disease.