<p>This paper presents novel findings on the influence of natural coir fiber interventions on the undrained shearing response of sands before, during, and after cyclic liquefaction. For this, constant volume simple shear tests were conducted on sand specimens with and without coir fibers, by varying the fiber content to 0.25%, 0.50%, and 0.75%. Fundamental mechanisms, like strain energy dissipation, pore pressure generation, shear strain accumulation, and stiffness degradation, were critically examined to establish the effects of coir interventions. Also, the real scale potential of utilizing natural coir fibers to mitigate cyclic liquefaction was demonstrated through model shaking table tests. Results showed that the cyclic resistance ratio increases by a maximum amount of 30% by adding 0.75% coir fibers to sand. In addition to increased liquefaction resistance, coir fibers improved the pre- and post-liquefaction shear strength of sand to a maximum extent of 42% and 74%, respectively. The ability of coir fibers to enhance the liquefaction resistance and strength regain after liquefaction was attributed to the additional confinement derived from the tensile pull of the fibers. Quantitative findings reported in this research offer guidance on addressing geotechnical problems at various stages of soil liquefaction through coir fibers, and propose their use in place of polymeric fibers.</p>