A photoelectrochemical system is a prominent way to harness and store solar energy. For this system, activity of the catalyst can be regulated by modifying the intrinsic electronic structure. In this manner, halide perovskites have shown excellent photoelectronic properties and remarkable tunability. Recent studies have observed a significant enhancement in photoinduced charge separation upon applying an external magnetic field to the photocatalysts. Spin-polarization of photoinduced electrons in a magnetic field results in a slower recombination rate (improved charge lifetime), thus giving a higher photocurrent. Studying the fundamentals of charge separation and the spin polarization effect due to an external magnetic field can provide an in-depth understanding of charge recombination and transfer mechanisms. The study of magnetic field enhanced electron spin polarization will further be utilized to design the new set of magnetic halide perovskites to achieve a highly efficient photocatalyst for solar water splitting.