Background <p>Chemoresistance, the primary cause of mortality among ovarian cancer (OC) patients, is a multifaceted process encompassing numerous biological phenomena. As sequencing technology continues to advance, single-cell sequencing has surfaced as a potent strategy to elucidate the pathogenesis of OC.</p> Methods <p>We examined single-cell sequencing data derived from five OC samples (three resistant and two sensitive) and identified an epithelial subcluster associated with chemotherapy resistance and poor prognosis. Using GSVA and cell communication analysis, we explored the unique biological functions and communication characteristics of this resistant subcluster. We performed high dimensional weighted gene co-expression network analysis and differential expression analysis to identify the hub genes of c3. Lastly, we investigated the correlation between the hub gene, CLIC3, and chemotherapy drug sensitivity. We also validated their involvement in specific pathways using TCGA data. The effects and primary mechanism to chemoresistance of CLIC3 was explored.</p> Results <p>We identified a cell subcluster, denoted as c3, strongly linked to chemoresistance and poor prognosis in OC. This subcluster demonstrated a correlation with both extracellular matrix (ECM) formation and angiogenesis signature, with CLIC3 identified as its key marker. The expression levels of CLIC3 exhibit a significant association with the sensitivity to various chemotherapeutic drugs in OC. Mechanistically, CLIC3 increases OC resistance to cisplatin by promoting integrin β1 redistribution and PI3K-AKT pathway.</p> Conclusions <p>This study offers a novel insight into the progression and chemoresistance of OC. Additionally, we identified a specific cell cluster highly associated with chemoresistance. The marker for this cluster, CLIC3, increases OC resistance to cisplatin by promoting integrin β1 redistribution and PI3K-AKT pathway and holds significant potential as a new therapeutic target for OC.</p>