AbstractSoft materials play a crucial role in small‐scale robotic applications by closely mimicking the complex motion and morphing behavior of organisms. However, conventional fabrication methods face challenges in creating highly integrated small‐scale soft devices. In this study, microfluidics is leveraged to precisely control reaction‐diffusion (RD) processes to generate multifunctional and compartmentalized calcium‐cross‐linkable alginate‐based microfibers. Under RD conditions, sophisticated alginate‐based fibers are produced for magnetic soft continuum robotics applications with customizable features, such as geometry (compact or hollow), degree of cross‐linking, and the precise localization of magnetic nanoparticles (inside the core, surrounding the fiber, or on one side). This fine control allows for tuning the stiffness and magnetic responsiveness of the microfibers. Additionally, chemically cleavable regions within the fibers enable disassembly into smaller robotic units or roll‐up structures under a rotating magnetic field. These findings demonstrate the versatility of microfluidics in processing highly integrated small‐scale devices.