We report on the controllable synthesis of diverse nanostructures using laser ablation of a metal target in a liquid medium. The nanodroplets generated by laser ablation react with the liquid and produce various nanostructures, such as hollow nanoparticles, core-shell nanoparticles, heterostructures, nanocubes, and ordered arrays. A millisecond laser with low power density is essential for obtaining such metal nanodroplets, while the target material, the reactivity of liquid medium, and the laser frequency are decisive for controlling the morphology and size of the nanostructures produced. This green and powerful technique can be extended to different material systems for obtaining various nanostructures.