The development of nanomaterials for wood coating is of considerable ecological and economic relevance that has enhanced performance and improved safety. This work presents the reflux assisted modified hydrothermal synthesis of TiO2/MgO mixed oxides nanoparticles for different concentration of Ti (9, 12, 15, 20, 30, 60)% and Mg (91, 88, 85, 80, 70, 40)%. Two phases were observed for all samples (i) cubical crystal structure for MgO lattice and (ii) rutile phase of TiO2. The crystallite size was estimated using both the Scherrer and Williamson–Hall methods. The crystallite size increases from 10.12 to 18.60 nm by increasing the concentration of Ti in the mixed oxides samples and compressive strain that originated from dopant incorporation during synthesis. The granular morphology of agglomerated particles in the form of clusters was observed with closely packed particles. The intensive peaks in the EDX result indicated the desired mass percentage of the elements (Ti, Mg and O) present in the samples. The redshift was observed in absorption spectra and reduction in bandgap was noted from 5.81 (9%Ti and 91%Mg mixed oxides) to 3.30 eV (30%Ti and 70%Mg mixed oxides) with increasing Ti concentration along with a slight increase in the bandgap of 3.93 eV for 60%Ti and 40%Mg mixed oxides sample. TGA results revealed that all samples are thermally stable with low weight loss for 50 to 600 °C temperature. The Nail wood was coated with a mixture of TiO2/MgO and sodium silicate and the results showed excellent fire resistance and self-extinguished within 50 s with low mass loss. The results indicated that 9% Ti and 91% Mg mixed oxides coated wood displayed lowest mass loss (4%) in just 38 s of self-extinguished as compared to the other samples. These results strongly correlated with structural and optical properties. These mixed oxides nanoparticles can enhance the performance of coating with long-term durability under real conditions and such materials can be used for industrial applications.