The association between glioblastoma (GBM) and human cytomegalovirus (HCMV) infection has been the intensely debated topic over the decades for developing new therapeutic options. In this regard, the peroxides from natural and synthetic sources served as potential antiviral and anticancer agents in the past. Herein, a concise and efficient strategy has been demonstrated to access a novel class of peroxides containing a spiro-isoxazoline to primarily investigate the biological activities. The synthetic compounds were evaluated for in vitro antiviral and antiproliferative activity against HCMV and glioblastoma cell line (GBM6), respectively. While compound 13m showed moderate anti-CMV activity (IC50 = 19 μM), surprisingly, an independent biological assay for compound 13m revealed its antiproliferative activity against the human glioblastoma cell line (GBM6) with an IC50 of 10 μM. Hence, the unification of an isoxazoline and peroxide heterocycles could be a potential direction to initiate the HCMV-GBM drug discovery program.