A novel series of dihydropyrano[3,2-c]quinoline derivatives 6a–q were synthesized and evaluated for their in vitro α-glucosidase inhibitory activities. All newly synthesized compounds displayed potent α-glucosidase inhibitory activity in the range of 10.3 ± 0.3 µM–172.5 ± 0.8 µM against the yeast α-glucosidase enzyme when compared to the standard drug acarbose (IC₅₀ = 750.0 ± 1.5 µM). Among these compounds, compounds 6e and 6d displayed the most potent α-glucosidase inhibitory activity (IC₅₀ = 10.3 ± 0.3 and 15.7 ± 0.5 µM, respectively). The kinetic analysis of the most potent compounds 6e and 6d revealed that compound 6e inhibited α-glucosidase in an uncompetitive manner (K_i = 11 µM) while compound 6d was a non-competitive inhibitor (K_i = 28 µM) of the enzyme. Then, the cytotoxicity of the most potent compounds (i.e., compounds 6a, 6d, 6e, 6 g, 6j, and 6l) were evaluated for toxicity using the breast cancer cell lines MDA-MB231, MCF-7, and T-47D by using a MTT assay, and no toxicity was observed.