Autophagy suppresses tumorigenesis by restoring a favorable energy balance. Activation of autophagic pathways has therefore sparked great interest as a target for cancer therapy. However, the targets of available autophagy activators are nonexclusively involved in autophagy in cancer cells, thus causing cytotoxicity in noncancerous tissues. Stimulation of anabolism and ensuing decreased energy levels in cancer cells are central to tumor-selective autophagy induction. Herein, we present black phosphorus quantum dots (BPQDs) with red blood cell membranes (RBCMs) cloaking (BPQDs@RBCMs) as activators of tumor anabolism for tumor-specific autophagy activation. The selective degradation of BPQDs@RBCMs releasing phosphate in the tumor microenvironment initiates autophagy by falling energy levels. In vivo assessments confirm that the BPQDs@RBCMs treatment effectively reduces overall tumor burden and alters metabolite profiles in tumor. Overall, this study underlines the potential utility of tumor-selective autophagy induction in cancer therapeutics.