The adsorption of the hydrogen peroxide (H$_2$O$_2$) molecule onto pure and (O or Be) vacancies of BeO nanotube (BeONT) was studied using density functional theory computations.As H$_2$O$_2$ approaches the pure BeONT and Be-vacancy BeONT, their adsorption releases −8.3 and −31.3 kcal/mol, respectively, indicating physisorption. Also, the electronic properties of the nanotube do not change significantly. But when H$_2$O$_2$ approaches the O-vacancy BeONT (V$_O$-BeONT), its adsorption releases −471.2 kcal/mol of energy, and electronic analysis showed that the VO-BeONT HOMO/LUMO gap reduces approximately about −29.9% and the electrical conductivity increases significantly. The reactivity of Be atoms of the defect is more towards H$_2$O$_2$ reduction to H$_2$O compared with perfect ones. Throughout the process of adsorption, the diffusion of the O atom of the H$_2$O$_2$ molecule was into the vacancy site, thereby dissociating the O–O and O–H bonds of H$_2$O$_2$ and forming H$_2$O. Therefore, VO-BeONT cangenerate electrical signals when the H$_2$O$_2$ molecule approaches, being a hopeful sensor.