The study demonstrates that mesoporous anatase nanofibers can be prepared via electrospinning of preformed TiO2 nanoparticles in an adequate solvent mixture without the use of any surfactant. A systematic study of several parameters influencing the fiber formation, that is, solvent composition, molecular weight of the polymer, TiO2 source, and humidity, was conducted to investigate the underlying physicochemical principles that determine the formation of the porous structure. The porosity of the fibers was characterized by nitrogen physisorption and SEM investigations with consistent results. It is proposed that the microphase separation of nanoparticles from the polymer produces a mesoscopic hybrid, resulting in pronounced mesoporosity after calcination. We believe that our study thus presents a general methodology to generate nonwovens of metal oxides with intrinsic mesoporosity based on electrospinning of preformed nanoparticles.