This article summarizes and reviews recent advancements in computational mechanics applied to wood and plant-based biocomposites. Emphasizing sustainability, these materials are gaining importance due to their excellent mechanical properties and low environmental impact. The paper highlights the complex hierarchical microstructure of wood and biocomposites, spanning from critical molecules like cellulose to macroscopic features, all of which influence mechanical performance and are considered in various modeling approaches. A range of computational modeling techniques is reviewed, including homogeneous, mesoscale, and microscale models, as well as molecular dynamics simulations. Homogeneous models directly address macroscopic failure mechanisms, while mesoscale models are able to capture the effects of material structures and provide insights into the interactions of a material’s constituents. Microscale approaches, for example, investigate the structural behavior of cellulosic fibrils, whereas molecular models examine atomic-level interactions. Despite significant progress in recent years, challenges remain in bridging scales, accounting for environmental factors such as moisture, and optimizing computational efficiency. This article offers a comprehensive overview of computational methods across these scales and provides an understanding of the strengths and limitations of each approach.