This paper presents an efficient colloidal approach to process CoFe2O4 and SiO2 nanoparticles into thin films for magnetic and magneto-optical applications. Thin films of varying CoFe2O4-to-SiO2 ratios (from 0 to 90 wt%) are obtained by sequential spin coating-calcination cycles from the corresponding nanoparticle dispersions. Scanning electron microscopy analysis reveals a crack free and nanoparticulate structure of the sintered films with thicknesses of 480-1200 nm. Results from the optical characterization indicate a direct band gap ranging from 2.6 to 3.9 eV depending on the SiO2 content. Similarly, the refractive indices and absorption coefficients are tunable upon SiO2 incorporation. In-plane measurements of the magnetic properties of the CoFe2O4 films reveal a superparamagnetic behavior with both Co2+ and Fe3+ contributing to the magnetism. Polar Kerr measurements show the presence of a spontaneous magnetization in the CoFe2O4 and CoFe2O4-SiO2 (with SiO2 < 50 wt%) films, pointing to magnetic anisotropy perpendicular to the substrate. The origin of this effect is attributed to the constrained sintering conditions of the nanoparticulate film and the negative magnetostriction of CoFe2O4.