Updated project metadata. Cells employ global genome DNA damage repair (GGR) to eliminate a broad spectrum of DNA lesions, including those induced by UV light. The lesion-recognition factor XPC initiates repair of helix-distorting DNA lesions, but binds inefficiently to lesions that cause poor helix distortion. How such difficult-to-repair lesions are detected in chromatin is unknown. Here, we identify the poly-(ADP-ribose) polymerases PARP1 and PARP2 as constitutive interactors of XPC. The close interaction between these proteins results in the PARylation of XPC at UV lesions, and an XPC-dependent stimulation of the poly-(ADP-ribose) response, which facilitates the recruitment of the poly-(ADP-ribose)-dependent chromatin remodeler ALC1. Both ALC1 and in particular PARP2 are required for the efficient clearing of difficult-to-repair DNA lesions. Our study offers key insights into the molecular mechanisms of GGR by revealing a molecular bookmarking system, which primes chromatin containing difficult-to-repair DNA lesions for efficient repair.