RIPK1 scaffold activity is known to have a pro-survival role in TNFα signaling. Najafov et al. discover an unexpected role for RIPK1 scaffold activity in mediating mTORC1 inhibition by AMPK during energetic stress. Mechanistic studies reveal that RIPK1 is involved in regulating TSC2 phosphorylation at Ser1387 by AMPK. Reduced phosphorylation of this site in RIPK1-deficient cells results in a chronically elevated mTORC1 activity and lysosomal dysfunction.