Hypoxia is an increasing concern along the Northeast Pacific continental margin, driven by oxygen (O₂) declines related to a warming climate. Despite a declining North Pacific O₂ inventory, historical observations of hypoxia on the central coast of British Columbia, Canada, were rare before 2020. However, recent observations from Queen Charlotte Sound (QCS)—a 120 km-wide shelf sea supporting an ecologically and economically significant ecosystem—indicate that hypoxia is now an emerging issue in this region. This study synthesizes regional observations from numerous platforms to describe O₂ distributions during 2022 and 2023, identifying persistent shelf-wide hypoxia during summer months, including periods of statistically defined extreme hypoxia. Comparisons with the hydrographic record from 2003–2023 show that O₂ concentrations were lower and hypoxia more common in 2022/23 than in previous years. Long-term deoxygenation trends of approximately 5–10 μmol kg⁻¹ per decade are identified at isopycnals representing QCS deep waters, in addition to seasonal and interannual variability of similar magnitude. On annual and seasonal timescales, upwelling strength, timing, and O₂ consumption modulate O₂ variability, while the offshore supply of O₂ modulates variability on interannual and decadal timescales. This low-frequency signal propagates from the Northwestern Pacific via North Pacific Gyre circulation with an 8-year lag. The North Pacific Gyre Oscillation (NPGO) is also identified as a strong driver of O₂ variability through its influence on upwelling. The regional emergence of hypoxia has resulted from progressive O₂ declines rather than a sudden shift, and projections suggest that summer hypoxia will become the norm by 2050 in the absence of regional O₂ recovery.