LAUSR

The organization of nanoparticles in constrained geometries has attracted increasing attention due to their promising structures and topologies. However, the control of hierarchical structures with tailored periodicity at different length scales and topology stabilization in a dynamic environment are very limited and challenging. Herein, through self‐assembly of cellulose nanocrystals (CNCs) within an in situ formed hydrogel sheath using a simple microfluidic strategy, a new breed of liquid crystal (LC) fibers with hierarchical core–sheath architectures, metaperiodic cholesteric alignments, and 3D topological defects, termed as liquid metacrystal (LMC) fibers, is created. The resulting LMC fibers not only exhibit vivid, tunable interference colors, and even inverse optical activity but also have a unique ability to precisely regulate linearly and circularly polarized light in a half‐sync/half‐async form. Furthermore, robust hydrogel sheath enables the LMCs with alignment stability and configuration programmability during drying, which endows the unprecedented freedom to tailor different optical appearances for polarization‐based encryption and recognition. This work opens an avenue toward the fabrication of length‐scale colloidal LCs with continuous and stable topologies and expands the application regimes of LC materials in chiral optics and smart textiles.