The rapid expansion of the Internet of Things (IoT) has intensified the need for self-sustaining sensor nodes that circumvent reliance on battery replacements and complex power management. Current off-grid energy solutions often depend on intricate fabrication processes and specialized materials, limiting their scalability and adaptability. Here, we present a self-powered sensing system that leverages the high flexibility and stability of carbon electrodes, combined with the superior photovoltaic performance of perovskite materials, to achieve efficient energy harvesting and storage. Supercapacitors provide durable power buffering, ensuring continuous operation in dynamic environments. Additionally, the device incorporates dual-mode sensing for temperature and mechanical strain, demonstrating reliable and responsive detection capabilities under indoor illumination conditions. By eliminating the need for complex manufacturing processes and corrosion-prone metal components, our design provides a scalable solution for next-generation autonomous sensing networks. This work offers a simplified yet robust approach to developing self-powered IoT nodes, with potential applications in smart infrastructure and environmental monitoring.