In this study, a novel strategy for accelerating the production of pumpable ice slurry (PIS) by using ozone micro–nano bubbles (O3-MNBs) was proposed. The effect of PIS containing sodium alginate (SA) and O3-MNBs on the preservation of small yellow croaker (Larimichthys polyactis) was investigated. The results indicate that using SA solution containing O3-MNBs instead of only SA solution resulted in quicker production of PIS by promoting ice nucleation and eliminating supercooling. The distribution and positive effect of O3-MNBs as a nucleation agent on freezing characteristics were discussed. Microbial concentrations, pH, total volatile basic nitrogen, and thiobarbituric acid reactive substance content were also examined. Storage in novel PIS (containing O3-MNBs) had higher performance than storage in flake ice or conventional PIS due to the strong bacteriostatic ability of O3. Therefore, O3-MNBs injection can be used as a novel method for PIS production and the preservation of fresh marine products.