Research has revealed that over 90% of duodenal ulcers and approximately 80% of gastric ulcers are linked to Helicobacter. pylori infections. Beyond ulcers, it can cause mild chronic gastric inflammation and may even lead to gastric cancer. Several diagnostic techniques have been developed to detect H. pylori, spanning bacteriological, genomic, isotope tracing, pathological, serological, and molecular methods. Despite their effectiveness, most of these methods necessitate specialized equipment and skilled personnel, limiting their application in early detection and prevention, which can have serious health and economic implications. Hence, there is an urgent need for a simple, rapid, highly specific, and cost-effective approach for detecting H. pylori. This study presents the first selection, identification, and biosensing application of the H. pylori surface protein Cag A and the development of a novel label-free electrochemical aptasensor used for signal enhancement to achieve the facile, rapid, and direct detection of the Cag A antigen using a conductive SA hydrogel as an efficient solid support on the ITO surface. The fabricated aptaprobe has a satisfactory selective recognition function toward the Cag A antigen via the DPV technique, even in the presence of a high concentration of co-existing elements. The aptasensor demonstrated an acceptable wide linear range (0.1-80 ng mL^-1), high sensitivity [22.64 mA log₁₀ (mL ng^-1) cm^-2)], a low sensing limit (0.17 ng mL^-1) and limit of quantification (0.54 ng mL^-1), and a rapid response time (∼14 min). Although clinical validation is needed to establish its clinical utility, the findings of our study are promising and encouraging.