Epigenetic mechanisms regulate gene expression programs during neurogenesis, but the extent of epigenetic remodelling during human cortical development remains unknown. Here, we characterize the epigenetic landscape of the human developing neocortex by leveraging Epi-CyTOF, a mass cytometry-based approach for the simultaneous single cell analysis of more than 30 epigenetic marks. We identify H3K27me3, deposited by Polycomb Repressive Complex 2 (PRC2), as the modification with the strongest cell type-specific enrichment. Inhibition of PRC2 in human cortical organoids resulted in a shift of neural progenitor cell (NPC) proliferation towards differentiation. Cell type- specific profiling of H3K27me3 not only identified neuronal differentiation genes in the human neocortex, but also extra-cellular matrix (ECM) genes. PRC2 inhibition resulted in increased production of the proteoglycan Syndecan 1. Overall, this study comprehensively characterizes the epigenetic state of specific neural cell types and highlights a novel role for H3K27me3 in regulating the ECM composition in the human developing neocortex.