The objective of this research was to fabricate a pH-sensitive packaging based on sodium alginate (SA) and apricot peel pectin (APP) with rose anthocyanins extracts (RAEs) by a casting method for monitoring grass carp (Ctenopharyngodon idellus) fish meat freshness. It revealed that RAEs were uniformly dispersed in film-forming matrix, which changed the mechanical strength (tensile strength: 44.95 MPa→35.76 MPa and elongation at break:69.84%→61.72%) and water vapor permeability (6.32 ×10⁻¹¹ g. m/m². s. Pa →8.10 ×10⁻¹¹ g. m/m². s. Pa) of the SA/APP film. With the incorporation of RAEs (5%−20%), the composite SA/APP/RAEs films exhibited higher thermal stability, superior antioxidant capacity, and stronger light barrier behaviors. In addition, the film containing 20% (w/w) RAEs (FRA20) exhibited a remarkable sensitivity to pH changes (pH 2–12). Furthermore, when applied for the grass carp freshness monitoring at 4 ℃, the light yellow appearance of FRA20 film suggested the beginning of fish spoilage, whereas the dark yellow appearance of FRA20 indicated the severe spoilage of the meat. A strong correlation (R² =0.983) was observed between the total volatile basic nitrogen content of the meat sample and the total color difference of FRA20, suggesting the great potential of FRA20 for grass carp freshness monitoring.