Metal intercalation and stacking engineering provide effective routes to enhance superconductivity in two-dimensional borophene-based materials. Here we focus on the $\mathit{AA}$-stacked Sr-intercalated coloring-triangle-lattice (CTL) bilayer borophene ($AA\text{−}{\mathrm{SrB}}_{18}$), identified from a systematic first-principles screening of metal-intercalated CTL bilayers. Among 20 dynamically stable metallic $M{\mathrm{B}}_{18}$ phases derived from 17 intercalated bilayers with $\mathit{AA}$ or ${AA}^{\prime }$ stacking, isotropic electron-phonon coupling calculations identify $AA\text{−}{\mathrm{SrB}}_{18}$ as the most promising superconducting candidate. We subsequently examine $AA\text{−}{\mathrm{SrB}}_{18}$ using fully anisotropic Migdal–Eliashberg calculations, which yield a $T_{\text{c}}$ of 22.2 K and reveal a weakly separated two-gap superconducting state associated predominantly with B-$\sigma$- and B-$\pi$-derived Fermi-surface sheets. The enhanced superconductivity relative to pristine CTL bilayer borophene originates mainly from Sr-induced strengthening of the electron–phonon coupling, dominated by low-frequency Sr vibrations and intermediate-frequency out-of-plane B phonon modes. In addition, $AA\text{−}{\mathrm{SrB}}_{18}$ hosts symmetry-protected Dirac crossings that are essentially unaffected by spin-orbit coupling, indicating robust topological metallic characteristics. These results establish $AA\text{−}{\mathrm{SrB}}_{18}$ as a promising two-dimensional platform exhibiting the coexistence of phonon-mediated superconductivity and nontrivial electronic topology, and highlight intercalant selection and stacking engineering as effective strategies for designing boron-rich superconducting materials.

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• Electronic structure
• Intercalation
• Structural properties
• Superconductivity
• 2-dimensional systems
• Superconductors
• Density functional theory
• First-principles calculations