This study explores valley polarization in twisted alternagnetism by applying an out-of-plane electric field. Alternagnetism, a type of magnetic ordering, allows for spin splitting without relying on relativistic spin-orbit coupling. Twisted magnetic van der Waals bilayers are ideal platforms for studying alternagnetism, with the symmetry of spin splitting (d-wave, g-wave, or i-wave) determined by the rotational symmetry. Valley polarization, which involves the polarization of electron spin and valley degree of freedom, is crucial for valleytronics and spintronics applications. By applying an out-of-plane electric field, the study demonstrates that valley polarization can be achieved in twisted alternagnetism. The electric field creates a layer-dependent electrostatic potential, leading to valley splitting and spin-valley polarization. This method is applicable to all five 2D Bravais lattices. The twisted tight-binding model confirms that the electric field can induce valley/spin-gapless semiconductor and half-metal states, which are important for spintronic and valleytronic applications. The study verifies the proposed method using first-principles calculations on twisted bilayer VOBr and monolayer Ca(CoN)₂, which are special twisted alternagnets. These materials exhibit d-wave alternagnetism and have zero total magnetic moment, with opposite spin magnetic moments in different layers. Applying an out-of-plane electric field induces valley splitting and spin-valley polarization, making them promising candidates for valleytronic applications. The findings provide new opportunities for innovative spintronics, twistronics, and valleytronics applications, highlighting the potential of twisted alternagnetism as a platform for multifunctional electronic devices.This study explores valley polarization in twisted alternagnetism by applying an out-of-plane electric field. Alternagnetism, a type of magnetic ordering, allows for spin splitting without relying on relativistic spin-orbit coupling. Twisted magnetic van der Waals bilayers are ideal platforms for studying alternagnetism, with the symmetry of spin splitting (d-wave, g-wave, or i-wave) determined by the rotational symmetry. Valley polarization, which involves the polarization of electron spin and valley degree of freedom, is crucial for valleytronics and spintronics applications. By applying an out-of-plane electric field, the study demonstrates that valley polarization can be achieved in twisted alternagnetism. The electric field creates a layer-dependent electrostatic potential, leading to valley splitting and spin-valley polarization. This method is applicable to all five 2D Bravais lattices. The twisted tight-binding model confirms that the electric field can induce valley/spin-gapless semiconductor and half-metal states, which are important for spintronic and valleytronic applications. The study verifies the proposed method using first-principles calculations on twisted bilayer VOBr and monolayer Ca(CoN)₂, which are special twisted alternagnets. These materials exhibit d-wave alternagnetism and have zero total magnetic moment, with opposite spin magnetic moments in different layers. Applying an out-of-plane electric field induces valley splitting and spin-valley polarization, making them promising candidates for valleytronic applications. The findings provide new opportunities for innovative spintronics, twistronics, and valleytronics applications, highlighting the potential of twisted alternagnetism as a platform for multifunctional electronic devices.