Semiconducting single-walled carbon nanotubes (s-SWCNTs) are direct bandgap semiconductors with a diameter-dependent band structure, ultra-high carrier mobility, and a massive specific surface area. These properties have enabled them to show outstanding performance and immense potential in the field of next-generation sensors. In photodetectors, they can efficiently convert light signals into electrical signals, allowing for highly sensitive and fast-response detection across a broad spectrum, especially in the near-infrared range. Their large surface area makes them extremely sensitive in gas sensors, where a change in electrical conductivity can detect trace amounts of toxic or explosive gases. Similarly, for biosensors, s-SWCNTs can be functionally modified to specifically bind with biomolecules, enabling high-precision detection of pathogens or proteins through changes in electrical or optical signals. Looking ahead, their flexibility, transparency, and biocompatibility mean that s-SWCNTs are poised to drive technological innovation in fields like security, smart homes, environmental monitoring, automotive electronics, and healthcare, becoming a core material for the next generation of high-performance smart sensors and microsystems.