Sweet potato (Ipomoea batatas [L.] Lam.) is one of the most important staple crops globally with particular cultural and economic significance in the Hawaiian Islands, yet the extent to which traditional cultivars persist remains unknown. The objective of this study was to elucidate the relationships between traditional Hawaiian sweet potato varieties and cultivars that originated elsewhere in the world. We sought to characterize genetic and phenotypic diversity of sweet potatoes represented in the Hawaiian Islands. To this end, a genetic assignment analysis was conducted on a sample of 77 individuals that consisted of traditional Hawaiian, USDA NPGS accessions, and recent herbarium samples. Additionally, voucher specimens of Hawaiian cultivars from the early twentieth century were assessed for variation in leaf morphology. We identified several inconsistencies within the Hawaiian-named varieties, as identically named varieties turned out to be genetically distinct, and similarly named voucher specimens varied in leaf morphology. Our findings call attention to the value of a set of Hawaiian sweet potatoes as “heirloom.” These genetically distinct traditional cultivars have unique value in local markets and present an opportunity to increase cultivar diversity in the markets and fields, support farmer income and diversified agriculture, all while contributing to reinvigoration of Hawaiian cultural heritage.