Interlayer Be-B bonding enhanced superconductivity driven by van Hove singularity and flat band in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>t</mml:mi> <mml:mtext>-Be</mml:mtext> <mml:msub> <mml:mi mathvariant="

Metal-doped borophenes offer a versatile platform for realizing topological superconductivity and investigating exotic quantum states. In this study, through extensive structural searches, we identify the $t\text{-Be}{\mathrm{B}}_{3}$ monolayer and its stacked bilayer as the lowest-energy configurations within their respective layered systems. Compared to the monolayer, the ${\mathrm{AB}}^{\ensuremath{'}\ensuremath{'}}$-stacked bilayer forms interlayer Be-B covalent bonds that not only enhance thermodynamic stability but also drive a topological phase transition---resulting in the emergence of Dirac points and topological surface states near the Fermi level. Remarkably, the ${p}_{z}$ electrons localized on the interlayer Be-B bonds induce van Hove singularities and a flat band, which strongly couple to out-of-plane phonon modes. This leads to a significant enhancement in electron-phonon coupling (EPC) strength---from 0.51 in the $t{\text{-BeB}}_{3}$ monolayer to 0.85 in the bilayer---and yields a threefold increase in the superconducting critical temperature (${T}_{c}$) from 10.3 to 30.2 K. These results highlight the pivotal role of interlayer bonding in tuning the electronic structure and EPC in borophene-based materials, offering a promising pathway toward the design of high-${T}_{c}$ topological superconductors.