Aqueous nanoparticle dispersions have been widely studied for their important industrial applications, including photocatalyst, coating, and casting. However, much less work has been conducted on nanoparticle dispersions in organic solvents, especially when co-dispersing with dissolved polymers. In this study, we explore TiO2/ZnO nanoparticle and poly(methyl methacrylate) (PMMA) co-dispersion in organic solvent anisole. To achieve uniformly dispersed suspensions, nanoparticle surface functionalization with nonanoic acid and 1-pentanol is conducted. Nonanoic acid has higher surface coverage on TiO2 and the two dispersants show similar surface coverage on ZnO. Heat treatment enhances the dispersant adsorption on the nanoparticle surfaces. For both TiO2/PMMA and ZnO/PMMA co-dispersions, higher solids loading leads to higher suspension viscosity. Higher volume fraction of nanoparticles in the nanoparticle plus PMMA solid phase results in lower viscosity, mainly by reducing the entanglement of the dissolved PMMA chains.