Abstract: Understanding the potential areas suitable for offshore mariculture is crucial to global seafood security. Here, we map the potential global offshore mariculture areas for 23 principal commercial finfish using an ensemble model. The model involves the temporal–spatial heterogeneity of environments and constraints of temperature-dependent hypoxia and cold edges of cultured finfish by metabolic index and lower thermal safety margin, respectively. Our results show that currently, there is 9.16 ± 1.22 million km² of potentially suitable area for offshore finfish mariculture. Under climate change, the potential suitable area will be reduced to between 86.7% and 91.7% of the current size by 2050. Compared to the decline in tropical regions, the expanded potential areas in temperate and polar regions will become more important for global seafood security. The potential offshore finfish mariculture area responds differently to global change among species, and cold-water finfish may benefit from global warming. Overall, despite changes in the distribution of global offshore mariculture areas and replacements of local potential mariculture species, offshore finfish mariculture still holds immense potential in the future.