Hydrogen, as a vital green energy source, poses a risk due to its flammability and potential for explosion. To mitigate this risk, the development of highly sensitive hydrogen gas sensors using organic semiconductor materials has been crucial. Conducting polymers, especially polyaniline, have shown promise in hydrogen sensor applications due to their conductivity and ability to detect low concentrations of gases. Various research efforts have focused on enhancing hydrogen sensitivity through improved detection limits and responsiveness. Designing efficient heterostructured conducting polymer sensors has been a successful strategy, with examples like MWCNT/PANI composites and polypyrrole sensors with TiO2 demonstrating enhanced hydrogen detection capabilities. Recent work on heterostructured sensors made of vanadium oxide and polypyrrole has shown significant improvements, indicating the importance of carrier mobility in conducting polymers for hydrogen sensitivity. Moreover, innovative sensor designs utilizing unique morphologies such as hollow tubes and 2D materials like graphene have shown promising results in improving sensor performance without the need for expensive additives. Research on polyaniline nanostructures, including hollow nanotubes, nanofibers, and thin films, is shedding light on the structure-properties relationship for highly sensitive hydrogen sensors. Overall, advancements in organic semiconductor-based hydrogen sensors offer a glimpse into a safer hydrogen energy future.