Protein palmitoylation is an essential post-translational modification necessary for trafficking and localization of regulatory proteins that play key roles in cell growth and signaling. Multiple oncogenes, including HRAS and SRC, require palmitoylation for malignant transformation. Lysophospholipase 1 (LYPLA1) has been identified as a candidate protein palmitoyl thioesterase responsible for HRAS depalmitoylation in mammalian cells. Seeking chemical tools to investigate LYPLA biochemical pathway involvement and potential roles in cancer pathogenesis, we conducted a fluorescence polarization-based competitive activity-based protein profiling (fluopol-ABPP) HTS campaign to identify inhibitors of LYPLA1 and the structurally related LYPLA2. HTS identified a lead triazole urea micromolar inhibitor, which we optimized as dual LYPLA1/LYPLA2 inhibitor ML211, and reversible compounds ML348 and ML349 that act as selective LYPLA1 and LYPLA2 inhibitors, respectively. These compounds represented an important advance in chemical tools for investigating the biological function(s) of LYPLA1 and LYPLA2. However, ML211, owing to its modest solubility, does not have demonstrated in vivo activity. With the goal of developing an irreversible, in vivo-active dual LYPLA1/LYPLA2 inhibitor, we investigated SAR around a carbamate scaffold, from which we optimized ML378, a dual LYPLA1/LYPLA2 inhibitor with nM potency and demonstrated peripheral in vivo activity.