A simple one-pot template-free synthesis was used to form porous Pt networks from the CO-induced self-organization of monodisperse primary Pt nanoparticles. Spherical, rod-shaped, knot-like, multibranched, and hyperbranched porous networks could be obtained under different conditions through changes in the reaction temperature and citrate ion concentration. The formation of these porous platinum networks could be rationalized by a mechanism where citrate ions and Chini-like platinum carbonyl clusters formed upon CO exposure are the most important contributors.