In this work, a kinetics‐integrated CFD model based on coupling computational fluid dynamics (CFD) and biokinetic was developed to guide the industrial scale‐up for fermentation of docosahexaenoic acid (DHA). Two‐substrate biokinetic equations for a 5 L bioreactor with oxygen and nitrogen source as limiting substrates were established, which were further coupled with CFD to simulate the biomass growth and lipid accumulation as well as flow field environment in the fermentation process. The coupled CFD‐biokinetic model can accurately reflect the changes of each relevant variable in the 50 L bioreactor under different operating conditions. The optimal working conditions of a 35 m3 bioreactor were predicted by this model and have secured the one‐step scale‐up of DHA fermentation, resulting in a biomass, lipid concentration, and DHA content in lipids of 99.2 g/L, 55.7 g/L, and 52.5%, respectively. This study thus provides an effective strategy for rapid industrial scale‐up of DHA production.