Mollusca, one of the most diverse animal phyla, plays essential ecological roles across marine, freshwater, and terrestrial environments. Despite their importance, molluscs have received limited attention in DNA-based systematic studies, with only about 10% of the estimated species represented in public DNA barcode databases. This gap hampers accurate identification. Catalonia, located in the north-eastern Iberian Peninsula, features a rich malacological history. However, a comprehensive molluscan DNA barcode reference library remains unavailable, hindering conservation and research efforts. To address this gap, we generated DNA barcodes for morphologically well-identified continental molluscs from the region. Our study includes 368 cytochrome c oxidase I sequences, corresponding to 47 families, 91 genera, and 168 nominal species and subspecies from Catalonia. We analysed genetic variation within and between taxa to assess molluscan diversity. Barcode gap analyses revealed that 88.8% of the 107 analysed species exhibit a barcode gap, supporting the efficacy of DNA barcoding for species discrimination. Additionally, we combined our sequences from the genera Abida and Chondrina with additional ones from BOLD and applied four species delimitation methods. These analyses yielded differing numbers of Molecular Operational Taxonomic Units (MOTUs) and highlighted incongruences between morphological and molecular data, underscoring the need for integrative approaches incorporating multilocus or genomic data, morphology, and ecological evidence. By expanding DNA barcode libraries, our findings provide a critical genetic resource for molluscan biodiversity assessment and lay the groundwork for future molluscan research supporting biodiversity conservation planning and monitoring.