Liquid crystal polymer (LCP) fibers hold great potential in enhancing the toughness of cement composites due to their excellent tensile strength. However, the hydrophobic and smooth surface of LCP fibers results in the formation of a weak interface between the fiber and cement matrix, limiting the full utilization of their extraordinarily high strength. To address this issue, we propose a novel approach through coating the surface of LCP fiber with polydopamine (PDA) to improve its interfacial bonding with cement matrix and reveal the underlying mechanisms in toughness enhancement as well. At first, the single fiber pullout test shows that the maximum pullout force increased by 136 % after modification under the optimal condition of a dopamine concentration of 2 g/L and a modification duration of 24 h, compared to the unmodified fiber. Mechanistic tests uncover that, from a microscopic perspective, the wettability and chemical reactivity of PDA-coated fibers are improved due to the introduction of active polar functional groups, and the surface roughness is also increased due to uneven deposition of PDA. These changes enhance the macroscopic resistance to fiber pullout during the debonding stage and contribute to the dissipation of more pullout energy during the pure friction stage, thereby maximizing the exertion of their high tensile strength. Accordingly, the mechanical flexural strength of fiber-reinforced cementitious composites (FRCC) is improved by the incorporation of PDA-coated LCP fibers, showing a notable 33 % increase with a value of 17.86 MPa in comparison to its unmodified counterpart.