pH-sensitive colorimetric indicator films are essential components of intelligent packaging systems. Alizarin, an organic dye with pH-responsive properties, has attracted attention as a visual indicator in intelligent packaging applications. Therefore, this study aimed to develop and evaluate the performance of an intelligent chitosan/alizarin film as an active packaging system with pH sensitivity, and to assess its antimicrobial and antioxidant activities. Alizarin was extracted from madder root with a molar absorptivity coefficient of ε = 5.5 and a yield of 3.43 mg/g dry weight, and incorporated into chitosan films at a concentration of 3%. Fourier Transform Infrared Spectroscopy (FTIR), surface morphology (SEM), antimicrobial activity (MIC, MBC, and IZ) against foodborne pathogens including E. coli, S. aureus, S. typhimurium, and L. monocytogenes, antioxidant activity (DPPH and ABTS), and color changes of the intelligent film were measured at pH 1 to 14 were investigated. FTIR and SEM analyses revealed that interactions between the amino groups of chitosan and the aromatic structure of alizarin led to structural modifications and increased surface roughness of the film. The film exhibited significant antimicrobial activity in MIC, MBC, and inhibition zone tests, particularly against Gram-positive bacteria (p<0.05). Additionally, DPPH and ABTS assays confirmed a significant enhancement in antioxidant activity (p<0.05). The film’s color response varied from yellow to purple across the pH range of 1 to 14, indicating high sensitivity to environmental changes. Overall, the chitosan/alizarin film, with its multifunctional properties—antimicrobial, antioxidant, and pH-responsive—represents a promising and practical candidate for the development of intelligent packaging systems to promote food safety.