Borohydrides (X\mathrmBH_4, X\mathrm=Li,\; Na,\; K) exhibit an “elemental synergy” effect, characterized by the high neutron absorption cross-section of boron and the excellent moderation capability of hydrogen, making them promising candidates for neutron shielding materials. However, the current lack of experimental and evaluated thermal scattering data for borohydrides in international nuclear data libraries hinders the accurate assessment of their shielding and moderation performance. In this study, material properties including lattice parameters, electronic structures, and phonon densities of states are calculated based on first-principles density functional theory. Subsequently, the corresponding S(\alpha, \beta) data and thermal neutron scattering cross-sections are developed. The simulated lattice parameters show good agreement with the experimental data. By comparing the electronic structures and phonon densities of states of X\mathrmBH_4, the coherent elastic, incoherent elastic, and inelastic scattering cross-sections for the cations X, B, and H are obtained. The results indicate that the thermal neutron cross-sections of the constituent nuclides in \mathrmXBH_4 exhibit significant differences depending on the cation X. To evaluate the impact of thermal scattering data on neutron shielding effects, a simplified fusion source model is employed using the OpenMC code to compare the leaked neutron energy spectra under different physical models. The results demonstrate that the Free Gas Model (FGM) provides an inaccurate description of neutron moderation due to its neglect of lattice binding effects. Furthermore, owing to the large incoherent scattering cross-section of hydrogen, the coherent elastic scattering cross-sections of the various nuclides have a negligible impact on the neutron energy spectrum. This research fills the gap in thermal neutron cross-section data for borohydrides and lays a foundation for further investigations into their application as neutron shielding materials. The datasets presented in this paper, including the ScienceDB, are openly available at https://www.doi.org/10.57760/sciencedb.j00213.00219.