In this work, we report an innovative and facile UV light-assisted synthesis of a nanocomposite based on silicon oxycarbide (SiOC) and tin nanoparticles. SiOC ceramic matrix, containing a conductive free carbon phase, participates in lithium-ion storage, and buffers the volume changes of Li-alloying/de-alloying material. The reported synthesis procedure through a polymer-derived ceramic route involves the preparation of a single-source precursor by UV crosslinking of a preceramic polymer in the presence of a tin precursor. Pyrolysis of this starting precursor at 1000 °C leads to a homogenous distribution of tin nanoparticles (25–35 nm) within the SiOC ceramic matrix, which is crucial for electrochemical stability of the material. SiOC/Sn nanocomposite tested as an anode for Li-ion battery exhibits high reversible capacity values (603 mAh g⁻¹ at the current density of 74.4 mA g⁻¹), outstanding rate capability (524 mAh g⁻¹ at 2232 mA g⁻¹), and superior stability (494 mAh g⁻¹ after 250 charge/discharge cycles).