Wood fibers are easily available as a waste material, and their incorporation into polymeric matrices results in a reduction of the cost of composite products. On the other hand, poly(3-hydroxybutyrate- co-3-hydroxyvalerate) is a biodegradable bacterial polyester and it is a potential candidate to replace conventional polymers in composites. The aim of this work was to evaluate the percentage of wood fiber to be incorporated in the poly(3-hydroxybutyrate- co-3-hydroxyvalerate) matrix and to investigate the effect of Struktol® as a processing aid on the final properties of biocomposites. Therefore, biocomposites of poly(3-hydroxybutyrate- co-3-hydroxyvalerate) were processed with addition of 0–40 wt% of wood powder with and without Struktol®. Mechanical properties, morphology, water absorption, and thermal stability were determined. The presence of Struktol® improved 104% the tensile modulus of the biocomposites when compared to the neat poly(3-hydroxybutyrate- co-3-hydroxyvalerate), reduced the water absorption for biocomposites up to 20 wt% of wood powder, and reduced the thermal stability. The biocomposites with 10 wt% of wood powder are the one with the best properties in relation to the others, independently of the presence of Struktol®.