Abstract The HSP90/R2TP quaternary chaperone assembles key cellular machines, including the three nuclear RNA polymerases and many non-coding RNPs. Here, we characterize the RNAs associated with R2TP and find that it binds many proteins co-translationally. Its co-translational interactome reveals potential clients and distinguishes clients bound only co-translationally, only post-translationally, or both.