To address the issues of brittleness, cracking, and relatively low strength in natural hydraulic lime (NHL), this study utilizes NHL5 and metakaolin as composite cementitious materials, and incorporates polyvinyl alcohol (PVA) fibers, polyethylene (PE) fibers, or basalt (BF) fibers to prepare high-ductility natural hydraulic lime-based composites. Its compressive and axial tensile properties, crack control abilities, and the reinforcing and toughening mechanisms of fibers are experimentally investigated. The results show that combinations of PVA or PE fibers with quartz sand or limestone sand endow the natural hydraulic lime with excellent strain-hardening and saturated multiple-cracking characteristics, significantly enhancing its tensile strength and ductility. Amongst, the combination of PE fiber and limestone sand increases the ductility up to 5.6%, while the joint-use of PVA fiber and both types of sand increases the ductility up to 4%. Both fibers can control the crack width to below 100μm, adding excellent crack control abilities as well as ultra-high deformation capacity into lime-based materials. The developed high-ductility natural hydraulic lime-based composites allow new options for the restoration of heritage buildings and new wall plastering projects.