The resulting nanosystem relieved hypoxia in tumor tissues, enhanced PDT efficiency, and amplified antitumor immunity induced by phototherapy. As a photosensitizer, CyI effectively killed the tumor by generating toxic singlet reactive oxygen species (ROS), while the addition of Met reduced oxygen consumption in tumor tissues, thereby evoking an immune response via oxygen-boosted PDT. Both in vitro and in vivo results illustrated that LCM effectively restricted the respiration of tumor cells to reduce tumor hypoxia, thus providing continuous oxygen for enhanced CyI-mediated PDT. Furthermore, T cells were recruited and activated at high levels, providing a promising platform to eliminate the primary tumors and synchronously realize effective inhibition of distant tumors.