Updated project metadata. Human cytomegalovirus (HCMV) is an important pathogen and a paradigm of viral immune evasion. Here, we describe a multiplexed approach to discover proteins with novel innate immune functions on the basis of their active proteasomal or lysosomal degradation during the early phase of HCMV infection. Using three orthogonal proteomic/transcriptomic screens to quantify protein degradation, we identified 35 proteins with high confidence that were enriched in known antiviral restriction factors. A final screen facilitated global analysis of the mechanism of viral immune-modulation by predicting which viral genes target >250 human proteins. Helicase-like Transcription Factor (HLTF), a DNA helicase important in error-free post-replication DNA repair, was rapidly degraded during infection and potently inhibited early viral gene expression. HCMV UL145, a protein of previously unknown function, recruits the Cullin 4 E3 ligase complex to degrade HLTF. Our approach and data will enable further identifications of innate pathways targeted by HCMV and other viruses.