Developing methods to assemble nanomaterials into macroscopic scaffolds is of critical significance at the current stage of nanotechnology. However, the complications of the fabrication methods impede the widespread usages of newly developed materials even with the superior properties in many cases. Here, we demonstrate the feasibility of a highly-efficient and potentially-continuous fiber-spinning method to produce high-performance carbon nanotube (CNT) fiber (CNTF). The processing time is <1 min from synthesis of CNTs to fabrication of highly densified and aligned CNTFs. CNTFs that are fabricated by the developed spinning method are ultra-lightweight, strong (specific tensile strength = 4.08 ± 0.25 Ntex⁻¹), stiff (specific tensile modulus = 187.5 ± 7.4 Ntex⁻¹), electrically conductive (2,270 S m²kg⁻¹), and highly flexible (knot efficiency = 48 ± 15%), so they are suitable for various high-value fabric-based applications.