<p>Responsive colorimetric materials exhibit significant potential for application in fields such as smart food packaging and wound monitoring. The functional integration of pH-indicators with material carriers enables breakthrough applications in nontraditional domains. In this study, we developed a novel material covalently grafted with a pH indicator that exhibited naked-eye pH-responsive color shifts. The covalent grafting of pH-responsive bromothymol blue onto carboxymethyl cellulose (CMC) was confirmed using advanced characterization techniques, including Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The pH-sensitive chromophore was covalently immobilized onto the CMC matrix through esterification, thereby establishing firm chemical conjugation. Moreover, a superior color-changing performance was achieved within several minutes in response to different pH values. The reusability and stability of this material offer distinct advantages over single-use pH test strips. pH-responsive colorimetric materials hold promise for efficient, noninvasive monitoring in intelligent packaging (food freshness), medical diagnostics (wound status, infections), biosensing, and environmental applications.</p>