TiO2 nanoparticles were in situ generated in one-dimensional poly(methyl methacrylate) PMMA nanohybrid fibers with excellent dispersion by using electrospinning combined with a sol-gel method followed by a mild hydrothermal treatment that preserves the properties of the polymer to the maximum degree. Detailed information of the preparation method, synthesis route, structure and properties of TiO2/PMMA nanohybrids is revealed. The possible rationale for the uniform formation of TiO2 nanoparticles in the PMMA matrix is discussed with respect to the role of the acid solvent trifluoroacetic acid (TFA) as well as the electrospun fiber structure in the sol-gel and hydrothermal process. The use of TFA in the preparation of electrospun precursor/PMMA solutions induces full hydrolysis of titanium alkoxide. The rapid electrospinning process suppresses the condensation reaction of the precursor. The strong hydrogen bonding interaction between hydrolyzed inorganic precursor and the polymer results in stable precursor/PMMA nanohybrids at ambient conditions. The solid fibrous polymer structure facilitates the generation and homogeneous distribution of nanosized TiO2 particles within the PMMA matrix at hot water conditions, which are ready to be used in biomedical and optical applications.