Ovarian cancer (OC) is the deadliest gynecologic malignancy, with platinum-based chemotherapy, such as carboplatin, remaining the standard first-line treatment. However, resistance to carboplatin poses a major therapeutic challenge, and its mechanisms are not fully understood.1 This study employed a novel validation-based insertional mutagenesis (VBIM) technique2 to identify genes driving carboplatin resistance in human epithelial OC cells. Our screen identified hematological and neurological expressed 1-like (HN1L/JPT2) as a novel contributor to resistance. HN1L overexpression increased resistance to carboplatin, whereas shRNA-mediated knockdown sensitized OC cells to treatment. Mechanistically, HN1L conferred resistance by activating nuclear factor κB (NF-κB) signaling. HN1L depletion also reduced anchorage-independent growth in vitro and tumorigenicity in an OC xenograft model. Immunohistochemical analysis revealed elevated HN1L expression across multiple stages of OC in both cell lines and patient tissues. Collectively, our findings identify HN1L as a previously unrecognized carboplatin resistance gene and suggest that targeting HN1L may offer a promising combination strategy with carboplatin for overcoming platinum resistance in OC.