Update information. Here we report that knockout of PPTC7, a mitochondrial matrix protein, hyperactivates BNIP3/NIX-mediated mitophagy in vitro and in vivo. Biochemically, the PPTC7 precursor is trapped by BNIP3 and NIX to mitochondrial outer-membrane, where PPTC7 scaffolds the assembly of the substrate-PPTC7- SCFFBXL4 holocomplex to degrade BNIP3 and NIX, forming a homeostatic regulatory loop. PPTC7 possesses an unusually weak mitochondrial targeting sequence to facilitate its outer-membrane retention and mitophagy control. Upon starvation, PPTC7 is transcriptionally upregulated in mouse liver to repress mitophagy, which critically maintains hepatic mitochondrial mass, bioenergetics and gluconeogenesis. Collectively, PPTC7 functions as a mitophagy sensor that integrates homeostatic and physiological signals to dynamically control BNIP3 and NIX degradation, thereby maintaining proper mitochondrial mass and cellular homeostasis.