Polycomb repressive complex 2 (PRC2) interacts with RNAs in cells, but there is noconsensus on how RNA regulates PRC2 canonical functions, including chromatinmodification and the maintenance of transcription programs in lineage-committed cells. Weassayed two separation-of-function mutants of the PRC2 catalytic subunit EZH2, defective inRNA binding but functional in methyltransferase activity. We find that part of the RNA-binding surface of EZH2 is required for chromatin modification, yet this activity isindependent of RNA. Mechanistically, the RNA-binding surface within EZH2 is required forchromatin modification in vitro and in cells, through interactions with nucleosomal DNA.Contrarily, an RNA-binding defective mutant exhibited normal chromatin modification activityin vitro and in lineage-committed cells, accompanied by normal gene repression activity.Collectively, we show that part of the RNA-binding surface of EZH2, rather than theRNA-binding activity per se, is required for the histone methylation in vitro andin cells through interactions with the substrate nucleosome.