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Engineered virus-like particles (eVLPs) are promising vehicles for transient delivery of gene editing agents. While extensive particle engineering has yielded efficient eVLPs, it remains underexplored whether engineering the cells used to produce eVLPs could further improve eVLP properties. We report an unbiased genome-wide screening approach to systematically investigate how genetic perturbations in producer cells influence eVLP production. This approach generates eVLPs loaded with guide RNAs that identify the genetic perturbation in the cell that produced a particular particle; the abundance of each guide RNA in eVLPs therefore reflects how the corresponding genetic perturbation influences eVLP production or cargo loading. We apply this approach to identify several genes that regulate eVLP cargo expression and loading into particles during the production process. Leveraging these insights, we engineer producer cells that support increased eVLP cargo packaging and a 2- to 9-fold increase in eVLP delivery potency across several cargo, particle, and target-cell types in cultured cells and in mice. Our findings suggest the potential of producer-cell engineering as a useful strategy for improving the utility of eVLPs and related delivery methods.