A magnetically tunable chromatic nanocomposite microactuator is proposed, which utilizes the optical and magnetic behaviors of self-assembled super-paramagnetic nanoparticles fixed in a polymeric microstructure. The original color can be programmed during a simple photolithography process, and the color can be changed just by applying and changing an external magnetic field. These microactuators are capable of acting as pixels in a color-changing pattern.