In this article, the effect of active coatings of flaxseed gum (FG) and sodium alginate (SA) containing carvacrol (CA) on the quality of turbot (Scophthalmus maximus) after storage at 4 °C for 18 days was evaluated. The experimental results showed that FG/SA-CA could effectively inhibit the growth of microorganisms. At the same time, FG/SA-CA reduced the value of odorous-related compounds including thiobarbituric acid reactive substances (TBARS), total volatile base nitrogen (TVB-N), and K values. The FG/SA-CA significantly delayed the oxidation of myofibrillar protein (MP) through controlling the development of carbonyl groups and maintaining a high content of sulfhydryl groups. Thus, FG/SA-CA inhibits the growth of spoilage microorganisms, maintains the structure of the protein, and extends the refrigerated shelf life of turbot.