Ocean acidification and warming are predicted to increase in the near future, but their effects and complex interactions on large pelagic fishes are not well known. Here, we determined the effects of elevated CO2 and temperature at projected end-of-century levels on activity levels, boldness, and metabolic traits in larval kingfish (Seriola lalandi). Kingfish were reared from the egg stage to 25 days post-hatch in a full factorial design of ambient and elevated CO2 (~500 µatm and ~1000 µatm) and temperature (21°C and 25°C). Activity levels were higher in fish from the elevated temperature treatment compared with fish reared under ambient temperature. However, elevated CO2 did not affect activity, and boldness was not affected by either elevated CO2 or temperature. Both elevated CO2 and temperature resulted in increased resting oxygen uptake rates compared to fish from ambient conditions, but neither affected maximum oxygen uptake rates. These findings suggest that elevated temperature has a greater impact on behavioral and physiological traits of larval kingfish than elevated CO2. However, elevated CO2 exposure did increase resting oxygen uptake rates and interacted with temperature in complex ways. Our results can inform science and aquaculture about the future outlook of large pelagic fishes.