Here we present a chemoproteomics fragment screening platform for identifying novel DUB-specific hit matter, that combines activity-based protein profiling with high-throughput chemistry direct-to-biology optimisation to enable rapid elaboration of initial fragment hits against OTU DUBs. Applying these approaches, we identify an enantioselective tool compound for OTUD7B, and validate it using chemoproteomics and biochemical DUB activity assays.