The California sea urchin fishery has been one of the most valuable commercial fisheries in the United States for several decades. The harvest of red sea urchins (Mesocentrotus franciscanus) originally began in California as a way to develop fisheries of underutilized species and was also seen as a way to curb destructive grazing on giant kelp (Macrocystis pyrifera). Unfortunately, over the last decade, this fishery has rapidly declined due to large-scale environmental stressors and is now considered fully exploited. In contrast to red urchins, purple sea urchins (Strongylocentrotus purpuratus) have very limited commercial value due to their smaller size and lesser roe yield. In recent years purple urchins have undergone a rapid population explosion and are now considered a pest as they voraciously overgraze kelp and outcompete other benthic invertebrates. The persistence of kelp loss has led to widespread ecosystem shifts to urchin barrens consisting predominantly of malnourished purple urchins with no economic value. Harvesting these urchins from barrens and enhancing their roe through aquaculture has the potential to transform these destructive grazers into high-quality seafood. Although practiced in several other countries, roe-enhancement aquaculture has not yet been applied in the United States. Using a land-based recirculating aquaculture system (RAS) in conjunction with two different formulations of prepared feed, we demonstrated that the malnourished roe of purple urchins collected from barrens (mean Gonad Index (GI) = 6.8 ± 0.7%) increased threefold, surpassing standard marketable yield (mean GI > 15%) after 9 wk of enhancement. Furthermore, roe enhancement on these prepared diets was significantly greater than on a diet of giant kelp (mean GI = 11.7 ± 1.2%). Analyses of proximate constituents and amino acid composition of gonad tissue also revealed differences among the roe of urchins fed the three diets during the trial period. In particular, one of the two prepared feeds resulted in a significantly greater amount of bitter-tasting amino acids in enhanced gonads compared to urchins fed whole kelp, while the other prepared formulation indicated a more natural flavor profile. Finally, consumption rate trials suggested differences in feeding rates as urchin gonads grew, showing the lowest consumption of feed occurring at the highest GI levels. Our results highlight an untapped potential to quickly produce a highly valued seafood product from seemingly low-value purple urchins. Echinoculture could thereby serve as a tool to help reinvigorate the California urchin industry, restore kelp forests from degraded barrens, and enhance the ecosystem services kelp forests provide to impacted coastal communities.