Protease-activated receptor 2 (PAR2) is a key regulator of tumor progression in various cancers and plays an important role in cancer cell proliferation, migration, invasion, and metastasis. Overexpression of PAR2 in cancer cells is associated with tumor progression and poor prognosis, making it an attractive therapeutic target. However, despite extensive research, PAR2 antagonists developed to date have limited selectivity and efficacy, with no successful clinical development. Most existing PAR2 antagonists primarily focus on inhibiting signal transduction. In this study, we found that punicalagin (PCG), a polyphenol derived from pomegranate, exhibits a unique dual mechanism: it not only inhibits PAR2 signaling but also promotes PAR2-specific internalization unlike existing PAR2 antagonists. PCG demonstrated potent and selective inhibition of PAR2 in vitro in colon cancer cell lines expressing endogenous PAR2. The anticancer effects of PCG were assessed in colon and breast cancer cell lines, representative models of PAR2-related cancers. To investigate the underlying mechanism, we employed Pitstop2, a clathrin-mediated endocytosis inhibitor, to determine the role of PCG-induced PAR2 internalization. Pretreatment with Pitstop2 effectively blocked PAR2 internalization and significantly reduced the inhibitory activity of PCG. Interestingly, Pitstop2 pretreatment increased the IC₅₀ of PCG for inhibiting PAR2-mediated calcium signaling by approximately threefold compared to PCG treatment alone. Moreover, the antitumor effects of PCG on cell viability and migration were significantly attenuated. This study is the first to demonstrate that punicalagin not only blocks PAR2 signaling but also induces PAR2 internalization, highlighting the critical role of internalization of PAR2 in its anticancer activity. These findings offer a novel strategy to overcome the limitations of current PAR2 antagonists and support the potential of punicalagin as a promising therapeutic candidate for PAR2-overexpressing cancers.