We present a tight-binding (TB) model for describing the electronic properties of the free-standing χ3 and β12 borophenes via the Slater–Koster approach. This model is constructed through s, px, py, and pz orbitals for each boron atom. The optimal Hamiltonian plus the overlap matrix are calculated by fitting the results of the TB model and density functional theory calculations using the least-squares method and the Levenberg–Marquardt nonlinear fitting algorithm. Considering three nearest-neighbors and a non-orthogonal basis set, this TB model accurately describes energy bands around high-symmetry k-points.