The development of bio-based materials marks a significant advancement in sustainable construction. However, concerns about the durability of these materials remain a key challenge. Water absorption is an indicator of durability in bio-based materials and warrants thorough investigation. In this context, this study aims at experimentally and numerically evaluating the phenomenon of water transport by capillarity action in partially saturated wood bio-concretes. The bio-concretes were produced with wood content of 40%, 45%, and 50% (used as bio-aggregates), and a cementitious matrix composed by cement, rice husk ash and fly ash. In addition to the capillary water absorption tests, the physical properties, including bulk density, open porosity, total water absorption, and drying shrinkage, were also evaluated. A non-linear finite-element-based model was employed to simulate the capillary transport phenomenon in bio-concretes by adopting a modified Darcy’s law. Based on the experimental results, the outcome of the inverse calibration allows to better understand the influence of the wood content on the Raleigh-Ritz pore size distribution and diffusivity behavior of the bio-concretes. The numerical results, which align closely with the experimental data, showed that bio-aggregates and their contents clearly modifies the diffusivity rule as a function of open porosity.