The main goal in the production of nanocomposites for optical applications is the uniform and nonagglomerated incorporation of nanoparticles into polymer matrices. Therefore, in this work gold nanoparticles have been generated by short-pulsed liquid phase laser ablation in methyl methacrylate (MMA) with or without dissolved poly(methyl methacrylate) (PMMA) followed by polymerization. The polymeric materials were then used in injection molding to form model nanocomposites for further analysis. It has been observed that the steric in situ-stabilization of nanoparticles by dissolved PMMA inhibits particle aggregation in MMA and due to particle quenching results in smaller nanoparticles than that achieved by working in pure MMA. Similar but even more pronounced stability issues have been highlighted on injectionmolded optical nanocomposites, revealing that the in situ-stabilization of nanoparticles with PMMA not only prevent an agglomeration in the colloidal state but could also prevent changes in particles dispersion along the entire processing chain ending in final 3D polymer samples. Besides the optical study of the characteristic plasmon peak of gold nanoparticles and the nonlinear absorption behavior for femtosecond laser pulses, XRD analysis revealed the appearance of atomic gold in a centrosymmetric Fm3m cubic structure.