IR‑783, a near‑infrared heptamethine cyanine dye, has been reported to possess cancer targeting and anticancer effects; Ηowever, the molecular mechanism by which IR‑783 exhibits anti‑breast cancer activity is unclear. In the present study, the inhibitory effects of IR‑783 on the proliferation and migration of breast cancer cells were investigated. Our results revealed that IR‑783 inhibited MDA‑MB‑231 and MCF‑7 cell proliferation in a dose‑ and time‑dependent manner by inducing cell cycle arrest at the G0/G1 phase. In addition, a Transwell assay demonstrated that IR‑783 treatment suppressed the migratory ability of MDA‑MB‑231 and MCF‑7 cells. Furthermore, IR‑783 treatment decreased the expression levels of matrix metalloproteinase (MMP)‑2 and MMP‑9 in MDA‑MB‑231 cells. Furthermore, IR‑783 induced MDA‑MB‑231 and MCF‑7 cell mitochondrial fission, and also decreased the levels of ATP. This was accompanied with a decrease in polymerized filamentous actin, which is the fundamental component of filopodia at the cell surface. Collectively, the results of the present study demonstrated that IR‑783 inhibited the proliferation and migration of MDA‑MB‑231 and MCF‑7 cells by inducing mitochondrial fission and subsequently decreasing ATP levels, resulting in cell cycle arrest and filopodia formation suppression. These findings suggest that IR‑783 may be developed into an effective novel drug for treating breast cancer.