<p>Near-infrared photoimmunotherapy (NIR-PIT) is a highly selective cancer treatment that induces rapid, membrane-disruptive cell death through the activation of IR700-conjugated antibodies by near-infrared (NIR) light. Although laser-based illumination systems are commonly used for NIR-PIT, whether a flexible, low-irradiance NIR light source can induce the characteristic photochemical and cytotoxic responses associated with NIR-PIT remains unclear. In this study, we investigated the feasibility of using a flexible, low-irradiance LED sheet as a wide-field NIR light-delivery platform for NIR-PIT. A plastic-based LED sheet can deliver wide-field NIR illumination at a substantially lower power density than conventional laser systems. The therapeutic efficacy of LED sheet-mediated NIR-PIT was evaluated in vitro using EGFR- and HER2-targeted cancer cell lines and in vivo using subcutaneous xenograft mouse models. In vitro analyses demonstrated that LED sheet irradiation induced characteristic features of NIR-PIT, including IR700 photobleaching, membrane disruption, and dose-dependent cytotoxicity, as confirmed by confocal microscopy, SYTOX Green staining, luciferase-based viability assays, and flow cytometry. In vivo, LED sheet-mediated NIR-PIT resulted in selective loss of IR700 fluorescence and significant reductions in tumor viability, as assessed by bioluminescence imaging, in both EGFR- and HER2-targeted tumor models. These findings provide proof-of-concept evidence that wearable, flexible LED-based illumination can induce key photochemical and cytotoxic features of NIR-PIT. By enabling wide-field and surface-conformal light delivery, LED sheet technology may broaden the technical versatility of NIR-PIT.</p>