Projections of how climate change will impact marine species and communities are urgently needed to inform management measures aimed at stemming biodiversity loss. In the coming decades, warming and deoxygenation of marine waters are anticipated to result in shifts in the distribution and abundance of fishes, with consequences for the diversity and composition of fish communities. Most projections to date have focused on temperature, but have not accounted for the confounding influence of oxygen and depth and are limited by the spatial resolution of global climate models. Here, we combine fisheries independent trawl survey data spanning the west coast of the USA and Canada with high resolution regional ocean models to make projections of how 40 groundfish species will be impacted by changes in temperature and oxygen in British Columbia (B.C.) and Washington. By leveraging coast-wide survey data, we quantify how temperature, oxygen, and depth jointly constrain the ranges of species. Then, using two high-resolution regional ocean-biogeochemical models, we make projections of biodiversity change at a high spatial resolution. Our projections suggest that, in B.C. and Washington, the number of species that are projected to decrease in occurrence is roughly balanced by the number that are projected to increase, resulting in considerable compositional turnover. Many, but not all, species are projected to shift to deeper depths as conditions warm, but low oxygen will limit how deep they can go. Thus biodiversity will likely decrease in the shallowest waters (< 100 m) where warming will be greatest, increase at mid depths (100 - 600 m) as shallow species shift deeper, and remain stable or decrease at depths where oxygen is limited (> 600 m). These results highlight the critical importance of accounting for the joint role of temperature, oxygen, and depth when projecting the impacts of climate change on marine biodiversity.