Photodynamic therapy (PDT) represents a promising strategy for tumor treatment. However, the development of PDT‐based antitumor therapies faces challenges stemming from the hypoxic nature of the tumor microenvironment and the limited penetration of photosensitizers. This study presents a novel class of antitumor nanoparticles, designated as ARLN‐FP, engineered to penetrate tumor tissues deeply and inhibit tumor growth through the generation of oxygen‐independent free radicals. With the encapsulation of IR780 and dimethyl 2,2′‐azobis(2‐methylpropionate) (AIBME) in the core of ARLN‐FP, near‐infrared (NIR) laser irradiation of ARLN‐FP with induced heat generation, which subsequentially led to the decomposition of AIBME and the production of free radicals without relying on oxygen. In vitro studies indicated that ARLN‐FP penetrated more than 100 µm into multicellular tumor spheroids, demonstrating its enhanced tissue permeability. Animal studies confirmed the anti‐tumor effects of ARLN‐FP‐mediated photonic thermodynamic therapy, where the oxygen‐independent radical formation contributed to successful tumor eradication, evidenced by a significant tumor inhibition rate of 90.8% after 22 days. This research presents a feasible method to overcome the limitations of traditional oxygen‐dependent photodynamic therapies, which offers a new approach to developing nanomedicines to overcome resistance in deep and hypoxic tumor regions.
