Abstract: Electrical control of the charge and spin degrees of freedom is the foundation of contemporary micro- and nano-electronics, and spintronics. However, the effective electrical control of the electron valley degree of freedom in solids is still under intensive research. This article presents our recent demonstration of the electrical control of the valley polarization in a pn junction consisting of a monolayer transition metal dichalcogenide and a magnetic semiconductor (Ga,Mn)As, via electrical spin injection.