A smart wound dressing based on carrageenan ( kappa C), locust bean gum (LBG), and cranberry extract (CB) for monitoring bacterial wound infections was developed and characterized using UV-vis spectroscopy, FT-IR, and SEM. The mechanical, swelling, cytotoxic and pH sensor properties were also investigated. UV-vis spectra demonstrated that the obtained kappa C:LBG:CB hydrogel film exhibited a visible change of colors as it was immersed in PBS solution pH 5.0, 7.3 and 9.0. The spectra of FT-IR suggested that chemical interactions had occurred between kappa C and CB extract. The obtained kappa C:LBG:CB hydrogel film exhibited adequate mechanical properties and a swelling behavior dependent on pH. Cytotoxicity tests indicated that kappa C:LBG:CB hydrogel film had dose-dependent cytotoxicity against NIH 3T3 fibroblast cells. The in vitro studies using Staphylococcus aureus and Pseudomonas aeruginosa demonstrated that the color changes of the kappa C:LBG:CB hydrogel film could be observed by naked eyes, confirming the potential use of the obtained hydrogel film as a visual system for monitoring bacterial wound infections.