This study aimed to explore and document putative exotic marine benthic invertebrate species in the Bijagós Archipelago, Guinea-Bissau, to enhance understanding of marine biodiversity and address the extent of marine species introductions. The research was conducted in the Bijagós Archipelago, a UNESCO Biosphere Reserve located in Guinea-Bissau. The study involved the region's first scuba-diving survey of marine biodiversity. DNA barcoding was employed to assist in the identification of benthic invertebrate species. Molecular phylogenetic analyses were conducted with the available DNA barcodes to ensure accurate taxonomic assignments, detect cryptic species, and investigate the phylogeography of the taxa. The survey resulted in the discovery of 28 new species records for the Bijagós Archipelago, including octocorals, scleractinians, hydroids, bryozoans, barnacles, and ascidians. Among these, six species were documented for the first time in the East Atlantic: