Depleting regulatory T cells (T _reg cells) to counteract immunosuppressive features of the tumor microenvironment (TME) is an attractive strategy for cancer treatment; however, autoimmunity due to systemic impairment of their suppressive function limits its therapeutic potential. Elucidating approaches that specifically disrupt intratumoral T _reg cells is direly needed for cancer immunotherapy. We found that CD36 was selectively upregulated in intrautumoral T _reg cells as a central metabolic modulator. CD36 fine-tuned mitochondrial fitness via peroxisome proliferator-activated receptor-β signaling, programming T _reg cells to adapt to a lactic acid-enriched TME. Genetic ablation of Cd36 in T _reg cells suppressed tumor growth accompanied by a decrease in intratumoral T _reg cells and enhancement of antitumor activity in tumor-infiltrating lymphocytes without disrupting immune homeostasis. Furthermore, CD36 targeting elicited additive antitumor responses with anti-programmed cell death protein 1 therapy. Our findings uncover the unexplored metabolic adaptation that orchestrates the survival and functions of intratumoral T _reg cells, and the therapeutic potential of targeting this pathway for reprogramming the TME.