To protect the environmentally friendly and renewable wood materials from the photodegradation caused by the ultraviolet (UV) light, different kinds of UV absorbers are typically applied to form a protective layer on the wood surface. However, most common UV absorbers are metallic oxides whose synthesis and use are not environmentally benign due to the heavy metal presence. In this work, graphitic carbon nitride (g-CN) nanosheets were chosen as a novel non-toxic, green and low-cost UV absorber. It was successfully applied to the wood surface using simple hydrothermal method. Experimental results confirmed presence of g-CN nanosheet coating on the wood surface. This coating was strongly bound to the wood surface by forming hydrogen bonds with underlying lignin and cellulose. After 15-day accelerated weathering test, the surface of g-CN coated wood (CW) did not show any visible discoloration, and the total color change (Delta E*) was less than 10%. g-CN nanosheets also enhanced wood thermal stability. Our research introduced a new UV absorber for wood products with efficient mechanism of UV protection. Resulting novel CW materials have good potential application prospects as functional wood products.