Flexible electromagnetic interference (EMI) shielding materials with ultrahigh shielding effectiveness (SE) are highly desirable for high‐speed electronic devices to attenuate radiated emissions. For hindering interference of their internal or external EMI fields, however, a metallic enclosure suffers from relatively low SE, band‐limited anti‐EMI responses, poor corrosion resistance, and non‐adaptability to the complex geometry of a given circuit. Here, a broadband, strong EMI shielding response fabric is demonstrated based on a highly structured ferromagnetic graphene quartz fiber (FGQF) via a modulation‐doped chemical vapor deposition (CVD) growth process. The precise control of the graphitic N‐doping configuration endows graphene coatings on specifically designable quartz fabric weave with both high conductivity (3906 S cm−1) and high magnetic responsiveness (a saturation magnetization of ≈0.14 emu g−1 under 300 K), thus attaining synergistic effect of EMI shielding and electromagnetic wave (EMW) absorption for broadband anti‐EMI technology. The large‐scale durable FGQF exhibits extraordinary EMI SE of ≈107 dB over a broadband frequency (1–18 GHz), by configuring ≈20 nm‐thick graphene coatings on a millimeter‐thick quartz fabric. This work enables the potential for development of an industrial‐scale, flexible, lightweight, durable, and ultra‐broadband strong shielding material in advanced applications of flexible anti‐electronic reconnaissance, antiradiation, and stealthy technologies.

Quartz fiber, a widely used reinforcer with high tensile strength and excellent heat resistance, can have more attractive electrical applications such as electromagnetic interference shielding, static dissipation, and strain sensing if it becomes conductive. Many attempts have been made to increase the electrical conductivity of quartz fiber by surface coating of conductive polymers or plating of metal films, but suffers from sacrificing flexibility and causing heavy metal pollution. Here we designed and massively produced a hybrid structure of graphene quartz fiber (GQF) by a forced-flow chemical vapor deposition (CVD) method, which combines the excellent conductivity of graphene and the extraordinary properties of quartz fiber. The as-fabricated flexible GQF exhibited high sensitivity, fast response (<0.5 s) and good durability (∼5000 cycles) to organic solvent vapor, suitable as a real-time biomimetic gas sensor. Furthermore, the massively produced GQFs can be knitted into meter-scale fabrics with tunable conductivity (sheet resistances of 0.2–10 kΩ/sq) and superior electrothermal conversion efficiency (up to 980 °C within a few seconds at 24 V), thus propelling its promising application in industrial electric heaters. We expect this hybrid GQF material will greatly expand the applications of traditional quartz fiber into an infusive multifunctional regime.