A four-component Ugi reaction (Ugi-4CR) utilizing formylphenyl boronic acids under mild condition was developed for the synthesis of arylboronic acid analogs. The reactions were performed in methanol and accelerated by microwave irradiation, which makes this strategy suitable for constructing boronic-containing chemical libraries. Two of the synthesized analogs were found to have cytotoxic activity against HepG2, MDA-MB231, and A549 cancer cell lines, demonstrating the potential application of this approach in developing novel boron-containing pharmaceuticals.