The tropical archipelago of Hawaii is famous for fostering a high proportion of island endemic lineages that have recently evolved across relatively small geographic distances, some diversifying on a grand scale through adaptive radiation. The archipelago has been termed a “conveyor belt” of volcanic islands which reach a carrying capacity of organismal diversity and subsequently submerge. This system predisposes endemic lineages to diversify from older islands to younger (progression rule), with diversity tending to be highest on younger islands. The Hawaiian blueberries (endemic Vaccinium species) clade is a dominant keystone group that occurs at high elevations across the island chain that appears to be highly diversified. The current treatment that comprises just three species is heavily disputed, having synonymized many species previously recognized. For over a century, outstanding questions have remained: (1) how many species of Hawaiian blueberries are there, and how can we define them? and (2) from what spatiotemporal origins did Hawaiian Vaccinium colonize the islands, and can we infer anything about the historical diversification of this group using current knowledge of island biogeography? Time-calibrated biogeographic analyses of a nuclear dataset (Angiosperms353) for 10 species of Vaccinium, including the three recognized species from Hawaiʻi, revealed a single dispersal from a temperate source ca. 5.1 MYA, a pattern typical of species-rich lineages and adaptive radiations in Hawaiʻi. To address species diversity of Hawaiian Vaccinium, aiming to provide a genetic reference for species delimitation, we used a target capture probe set built from the blueberry genome (V. corymbosum) to genotype by sequence 179 Hawaiian specimens representing the full morphological and geographic diversity of the group. 37,000 snps were called using the bilberry genome (V. myrtillus) as a reference, a species closely related to Hawaiian Vaccinium. SNPs were used to construct a maximum likelihood, concatenated (IQTree) and coalescent (SNAPP) phylogenetic trees of Hawaiian Vaccinium. Based on these analyses, we conclude that the current taxonomy of three species of Hawaiian Vaccinium does not adequately represent patterns of phylogenetic and morphological diversity. We detected more than 20 morphologically distinct lineages that may represent an adaptive radiation. Biogeographic analyses reveal a general pattern of migration from older islands to younger, with the highest diversity concentrated on the youngest islands, in agreement with studies of other Hawaiian lineages.