Sol–gel-derived silica–titania (SiOx–TiOy) films were investigated as functional oxide thin films for surface microstructuring and photonic components. High-refractive-index SiOx–TiOy layers (n ≈ 1.8) were deposited by dip-coating on glass and silicon substrates and patterned by photolithography followed by inductively coupled plasma reactive ion etching (ICP-RIE). The study focused on pattern transfer at the photoresist/oxide interface and on the effect of lithographic and etching parameters on surface morphology, sidewall profile, and optical response. Exposure dose, development time, and post-lithography thermal treatment were evaluated for AZ 15nXT masks formed on SiOx–TiOy layers. Controlled ICP-RIE processing enabled the fabrication of rib structures with widths from 1.2 to 24 μm and heights from 14 to 170 nm. SEM/FIB analysis showed smooth rib surfaces and step-like sidewall profiles, confirming effective transfer of the resist pattern into the oxide layer. The microstructured films were then optically validated in the visible spectral range using straight and curved rib waveguides. Single-mode guiding was obtained for 1.5 μm-wide ribs with a height of 20 nm, and a Mach–Zehnder interferometer was fabricated using these parameters. Optical losses as low as 1.8 dB/cm at 532 nm were measured. The results show that sol–gel-derived SiOx–TiOy films can be patterned by scalable lithography and dry etching into oxide microstructures with controlled geometry and functional optical performance.