Metastasis is one of the defining features of pancreatic ductal adenocarcinoma (PDAC) that contributes to poor prognosis. In this study, the palmitoyl transferase ZDHHC20 was identified in an in vivo short hairpin RNA (shRNA) screen as critical for metastatic outgrowth, with no effect on proliferation and migration in vitro or primary PDAC growth in mice. This phenotype is abrogated in immunocompromised animals and animals with depleted natural killer (NK) cells, indicating that ZDHHC20 affects the interaction of tumor cells and the innate immune system. Using a chemical genetics platform for ZDHHC20-specific substrate profiling, a number of substrates of this enzyme were identified. These results describe a role for palmitoylation in enabling distant metastasis that could not have been detected using in vitro screening approaches and identify potential effectors through which ZDHHC20 promotes metastasis of PDAC. Display omitted •ZDHHC20 is identified as mediator of PDAC metastasis•ZDHHC20 KO phenotype is abrogated in immunocompromised animals•Substrates of ZDHHC20 are identified using a chemical genetics platform Tomić et al. uncover regulators of PDAC metastasis and validate the pivotal role of ZDHHC20. Despite no impact on in vitro cell phenotype and primary tumor growth, ZDHHC20 depletion curbs metastasis in mice. This effect is dependent on the immune system, particularly natural killer cells.