Special Issue at Beilstein Journal of Nanotechnology that addresses laser material processing in liquids as an advanced, environmentally friendly approach for the synthesis and modification of nanomaterials. It covers pulsed laser ablation, fragmentation, and melting in liquid environments, enabling the production of surfactant-free, high-purity nanoparticles with controlled composition and morphology. Contributions span experimental techniques, in situ diagnostics, theoretical modeling, and numerical simulations, offering insight into fundamental mechanisms and process optimization. The issue further explores applications in catalysis, energy conversion, biomedicine, sensing, and functional nanocomposites, highlighting the versatility and scalability of laser-based liquid-phase nanomanufacturing.