Timber structural members have been widely adopted and used in construction due to their inherent characteristics. The main objective of this work is to assess the performance of timber beams with GFRP pultruded beam reinforcement subjected to flexure. A finite element model (FEM) using ABAQUS FEM software is developed, aiming to provide a benchmark modelling procedure. The modelling method considers the fundamental role of the connections among timber beams, the reinforcing GFRP pultruded profile (adhesive and screw connections), and the grain direction in the timber. To understand the influence of the grain direction, different angles of deviations between the longitudinal direction (along the grain) and the beam axis are considered. The robustness of the developed FEM procedure is validated by the experimental results of timber beams with and without GFRP pultruded reinforcement under flexure. It is demonstrated that the angle of deviation (grain deviation) produces high reductions in the strength of unreinforced timber beams. However, this effect is minimal for GFRP-reinforced timber beams. The experimentally derived benchmark FEM procedure can be used as a computational tool for timber beams with GFRP pultruded reinforcement to capture the capacity, failure mode, and load–displacement response.