<p>Helical architectures are ubiquitous in nature and inspire the design of flexible fibers with unique functionalities. However, conventional fabrication methods often fail to combine structural precision with scalable production. Here, we present a non-isometric coaxial wet-spinning strategy that couples rope-coil and shell-limited domain effects to continuously produce helical fibers. Counter-directional shear induces interfacial instability in the inner phase, driving its spontaneous folding into helices stabilized by a rapidly crosslinked rigid shell. Using polyurethane (PU) and alginate (Alg) as the inner and outer phases, respectively, we fabricate continuous and controllable PU helical fibers (PU-HF) by extrusion into a CaCl₂ coagulation bath, followed by hydrogel removal. Incorporating a reverse twisting process yields self-shrinking tubular fibers (PU-RHF) with dynamic thermal regulation, dissipating heat during motion and retaining warmth at rest. The integration of carbon nanotubes (CNT) further produces artificial muscle fibers (CNT/PU-HF) that exhibit large actuation strokes and rapid responses to organic solvents, enabling real-time leak detection. This versatile and scalable approach establishes a modular platform for high-performance flexible fibers, overcoming cost, stability, and continuity bottlenecks in microfluidic spinning and template winding methods, thereby advancing the development of intelligent textile technologies.</p> Graphical Abstract <p></p>