During sardine fish sauce production, salt concentration needs to be maintained at a specific level to inhibit the growth of undesirable microorganisms. Here, we employed pressurized CO₂ to control microbial growth in fish sauce. Fish sauces prepared at 30 °C for 6 months under 1–5 MPa pressurized CO₂ with 10% NaCl (FS_CO2) were compared to those produced under atmospheric pressure with 10–20% NaCl (FS_con). FS_con with 20% NaCl had a slight putrefied odor, whereas FS_CO2 exhibited a favorable odor despite its low NaCl concentration. In FS_CO2, bacterial count, biological amine content, and pungent organic acids decreased while free amino acid content increased compared to the control. Sensory evaluation indicated the FS_CO2 had weaker rancidity, fish-like, putrefactive, and pungent odors but an enriched dashi-like odor. These results show that pressurized CO₂ application can produce a salt-reduced, amino acid-enriched, and sensorially ameliorated sardine fish sauce.