The chemical treatments applied to some lignocellulosic resources commonly used as building materials can influence their mechanical performance during service, and hence, this effect should be studied for structural safety reasons. In this piece of work, prismatic samples of Dendrocalamus asper bamboo were treated in a vacuum/pressure process with disodium octaborate tetrahydrate (DOT) solutions and the corresponding mechanical performance was compared with non-treated and water-treated samples. Full penetration of boron was achieved, with DOT retentions of 14.79 kg m−3 and 21.79 kg m−3 for 5% and 8% (wt/wt%) solutions, respectively. Dynamic modulus of elasticity (MOE), static MOE, and compressive modulus of elasticity of the material, with values between 23.3–24.0, 15.9–16.2, and 26.2–27.2 GPa, respectively, were statistically equivalent for all the analyzed treatment conditions. However, a significant influence of the treatment could be observed on the specific compressive strength of bamboo, showing an increase of 35.3% for the 5% solution and 30.6% for the 8% solution. Although without statistical difference among the treatments, similar behavior was observed on the specific modulus of rupture (MOR) under flexural loading, with an increase of up to 10.1% in relation to the reference for the treated samples. The results achieved in the present study from nondestructive excitation pulse, three-point bending, and axial compression tests demonstrated that mechanical behavior of bamboo was preserved or even enhanced by the proposed treatments based on disodium octaborate tetrahydrate.