Photodynamic therapy (PDT) induces photochemical reactions, resulting in the destruction of tumor cells via singlet (S1) oxygen production. This cellular destruction occurs specifically in tumor cells, following selective accumulation of a photosensitizer and its excitation by a specific wavelength. Verteporfin (VP) is a second-generation photosensitizer that is currently being used worldwide in PDT to treat age-related macular degeneration. In addition, clinical trials with VP-PDT demonstrated anti-tumor efficacy and overall safety when used to treat locally advanced pancreatic cancer. In the present study, we examined the anti-tumor effect of VP-PDT on gastric cancer (GC) cell lines in vitro to conduct an initial assessment of its potential clinical applicability to this specific type of cancer. We evaluated the viability of MKN45 and MKN74 cancer cell lines after VP-PDT exposure and calculated the half maximal effective concentration (EC50) values for VP. Apoptosis in VP-PDT-exposed GC cells was observed. Furthermore, the EC50 values for a 30-min treatment with VP (2.5 J/cm2 of 660 nm LED light) were 0.61 and 1.21 µM for MKN45 and MKN74, respectively. When VP treatment times were increased, the EC50 values decreased. In conclusion, VP-PDT may be developed as an effective treatment for GC.