Three-dimensional (3D) boron configurations are scarce in small boron-based clusters. Herein, we employed the particle swarm optimization (PSO) algorithm to design a unique O_h-symmetric cubic Li₈B₆ structure, in which eight lithium atoms form a cubic framework centered by a B₆ octahedron. This geometry exhibits exceptionally high stability. Its fragmentation energy (Ef), computed at the CCSD(T)/def2-TZVPPD level, is 2.26 eV, at least 0.29 eV larger than that of adjacent lithium-boron complexes, such as Li₆B₆ (1.97 eV), Li₇B₆ (1.58 eV), Li₉B₆ (1.01 eV), and Li₁₀B₆ (1.65 eV). Moreover, a substantial energy gap of 2.36 eV (at PBE0 level) further contributes to its stability. Molecular dynamics (MD) simulations confirm the structural integrity of this cluster remains even at 1000 K, underscoring its remarkable thermal robustness. NBO analysis reveals significant electron transfer from the lithium framework to the boron core, suggesting that the global minimum structure can be conceptually represented by the formula Li₈⁸⁺B₆^8-. Detailed electronic analysis shows that this cluster exhibits superatomic character, with the electronic configuration of 1S²1P⁶2S²1D¹⁰2P⁶. Our findings propose a strategy for constructing spatial architectures in small boron-based clusters and introduce a new member to the superatomic family.