Large-scale genomic screenings greatly advanced our understanding of the genetic basis of schizophrenia. However, how this translates into neurobiological functioning is not clear. Therefore, we aimed to characterize the function of robust susceptibility gene zinc finger protein 804A (ZNF804A), using a model system of relevant cell type and neurodevelopmental timepoint. Based on previous findings, we hypothesized a role for ZNF804A in local protein translation. CRISPR/Cas9-mediated mutation of the risk gene led to increased synapse formation in human induced pluripotent stem cell (hiPSC)-derived developing glutamatergic forebrain neurons as assessed by high-content confocal imaging. Further, mass spectrometry analysis showed an increased recruitment of ribosomes to mutation neurites. Surface sensing of translation (SUnSET) screening complemented this by demonstrating an increased efficiency of local protein synthesis. Overall, these results introduce a novel cellular function for ZNF804A in a model system relevant to schizophrenia, uncovering some aspects of its neurobiology. Ultimately, findings of this study may aid to identify common mechanisms of susceptibility genes.