Phosphorylation is often used to promote protein ubiquitylation, yet we rarely understand quantitatively how ligase activation and ubiquitin (UB) chain assembly are integrated with phosphoregulation. Here we employ quantitative proteomics and live-cell imaging to dissect individual steps in the PINK1 kinase-PARKIN UB ligase mitochondrial control pathway disrupted in Parkinson’s disease. PINK1 plays a dual role by phosphorylating PARKIN on its UB-like domain and poly-UB chains on mitochondria. PARKIN activation by PINK1 produces canonical and noncanonical UB chains on mitochondria, and PARKIN-dependent chain assembly is required for accumulation of poly-phospho-UB (poly-p-UB) on mitochondria. In vitro, PINK1 directly activates PARKIN’s ability to assemble canonical and noncanonical UB chains and promotes association of PARKIN with both p-UB and poly-p-UB. Our data reveal a feedforward mechanism that explains how PINK1 phosphorylation of both PARKIN and poly-UB chains synthesized by PARKIN drives a program of PARKIN recruitment and mitochondrial ubiquitylation in response to mitochondrial damage. Display omitted •PINK1-PARKIN pathway is dissected via quantitative proteomics and live-cell imaging•PINK1-activated PARKIN synthesizes multiple chain linkage types in vitro and in vivo•PINK1 phosphorylates PARKIN to activate E3 and poly-UB to promote their interaction•The data suggest feedforward PINK1 PARKIN activation and recruitment to mitochondria Ordureau et al. describe a feedforward mechanism that explains how PINK1 phosphorylation of both PARKIN and PARKIN-synthesized ubiquitin chains drives PARKIN recruitment and mitochondrial ubiquitylation in response to mitochondrial damage, a process that is disrupted in Parkinson’s disease.