With the aid of DFT calculations, novel inorganic complexes of group III phosphide (XY)12 (X = Al, B and Y = P) nanoclusters are theoretically designed and explored through exohedral doping with alkaline earth metals (Be, Mg, and Ca). The HOMO-LUMO gaps of the proposed novel inorganic complexes are narrowed significantly due to the increase in the energies of HOMOs. The results show that doping of alkaline earth metal over phosphide nanocluster causes shifting of excess electrons from the metal atom towards the nanocluster and breaks the centrosymmetry of the nanocluster. The doping profoundly increases the NLO response of the complexes. The first hyperpolarizabilities (βo) up to 7.8×104 au are calculated for the complexes as compared to the zero βo value of the pristine nanocage. These interesting results will attract more research interest in alkaline earth metal doped inorganic fullerenes complexes for the potential use in novel opto-electronic and high performance NLO materials and further the experimental research.