1-Deoxynojirimycin, an α-glucosidase inhibitor, possesses various biological activities such as antitumor, antidiabetic, and antiviral effects. However, the application of 1-deoxynojirimycin is restricted by its poor lipophilicity and low bioavailability. In this study, three 1-deoxynojirimycin derivatives (<b>8</b>-<b>10</b>) comprising 1-deoxynojirimycin and kaempferol were designed and synthesized to modify their pharmacokinetics and improve their antitumor efficacy. Among them, compound <b>10</b>, a conjugate of 1-deoxynojirimycin and kaempferol linked through an undecane chain, exhibited excellent lipophilicity, antiproliferative effects, and α-glucosidase inhibitory activity. Compared with 1-deoxynojirimycin, kaempferol, and their combination, compound <b>10</b> downregulated cyclooxygenase-2 (COX-2) expression, arrested the cell cycle at the S phase, induced cellular apoptosis, and inhibited the migration of MCF-7 cells. Moreover, further investigation indicated that compound <b>10</b> induced MCF-7 cell apoptosis through a mitochondrial-mediated pathway via the loss of mitochondrial membrane potential. This led to increasing intracellular levels of reactive oxygen species (ROS) and Ca<sup>2+</sup>, the downregulation of Bcl-2 expression, and the upregulation of Bax levels.