Electronic as well as nonlinear optical properties (first hyperpolarizabilities) of boron phosphide nanoclusters doped with first row transition metals (Sc–Zn) are explored using density functional theory (DFT) calculations. Four different doping sites (b64, b66, r4, and r6) of the B12P12 nanocluster are considered for doping of the transition metals. Computational results revealed that these transition metals doped boron phosphide complexes are highly stable, and their HOMO–LUMO energy gaps are considerably reduced as compared to the pristine B12P12 nanocage. The highest interaction energy (–74.42 kcal mol–1) is observed for [email protected]4-B12P12 complex. The lowest HOMO–LUMO energy gap (1.44 eV) is computed for [email protected]64-B12P12 complex. Moreover, adsorption of the first-row transition metals (Sc–Zn) on the surface of B12P12 nanocluster significantly enhanced the nonlinear optical response of the resultant complexes. The highest static first hyperpolarizability value (4.4×104 au) is computed for [email protected]4-B12P12 complex. Moreover, frequency dependent hyperpolarizability calculations are also performed to evaluate the practicality of the transition metal doped boron phosphide ([email protected]12P12) complexes. The highest electro-optical Pockels effect (EOPE) value of 4.4×105 au is computed for [email protected]4-B12P12 complex while [email protected]6-B12P12 gives the highest second harmonic generation (SHG) value of 1.1×105 au. This study will be advantageous for providing guidance in further designing of new high-performance nonlinear optical (NLO) materials.