Driven by the quest for greener and more sustainable materials, the presented review analyzes recent studies in which wood and wood-based materials were combined with carbon nanomaterials in the form of carbon nanotubes and graphene. The analysis shows a close kinship between these two carbon-based materials. The first studies have shown that wood may be directly transformed into sp2-bonded carbons, i.e., form graphene-like structures. Further, it has been demonstrated that both carbon nanotubes and graphene can be used to coat or infiltrate wood and processed wood-based materials such as flexible wood sponges or biochars. Thanks to the unique electrical, mechanical, thermal, and wetting properties of graphene and carbon nanotubes, their wood-based nanocomposites were shown to have many potential applications in green electronics area or as nanodevices. Finally, a new range of studies in the area of wood composites showed that carbon nanomaterials integrated into wood-based boards could improve the properties of the former ones. The presented review shows that this emerging area of research on wood-based materials, graphene, and carbon nanotubes is highly promising and interesting in the context of new applications and future perspectives for sustainable development.