Electromagnetic interference (EMI) shielding materials play a crucial role in safeguarding electronic devices from external interference, ensuring their stable operation. Despite their effectiveness, traditional metallic EMI shielding materials face significant limits, such as high weight density, rigidity, and limited adaptability to complex circuitry. In this study, a lightweight, flexible carbon nanotube (CNT) fabric with superior EMI shielding performance was developed through the scalable preparation of CNT fibers and knitting of CNT yarns. The CNT fibers demonstrated excellent specific tensile strength (25.3 cN/dtex) and high electrical conductivity (3634.2 ± 114.0 S/cm). The resulting CNT fabric achieved an EMI shielding effectiveness of 66.8 dB for a single layer and 111 dB for multiple layers while maintaining an ultralow density of 0.2 g/cm3. Additionally, the CNT fabric was durable to withstand repeated bending and washing. When applied as the EMI shielding layer in coaxial cables, the CNT fabric delivered comparable signal transmission performance to that of copper while reducing the mass of the shielding layer by 32.1%. These comprehensive properties position CNT fabric as a promising alternative to conventional metal-based shielding materials, with broad application potential in aerospace, electronics, and related fields.