As defined by the United Nations, "clean water and sanitation" is one of the 17 sustainable development goals for the improvement of sustainable living. Pollution prevention and the acquisition of clean water are urgent demands that require the joint cooperation of all nations. From a practical standpoint, it is important to develop sustainable systems for oil/water separation because mixtures of oil and water often threaten the environment and endanger biological systems. For example, major oil spills can destroy entire ecosystems and the economic activities that depend on them. [1] Separating oil and water is currently a global challenge. [2][3][4][5][6][7][8][9][10][11][12][13][14] Thus, more effort is required for the construction of effective systems based on functional materials, devices, and techniques that facilitate the sustainable separation of oil/ water mixtures (O/W-Ms) to obtain clean water and to enable the recycling of expensive oil. Water is often "polluted" by oil and forms oil/water layered mixtures (O/W-LMs), oil-in-water emulsions (O/W-Es), and water-in-oil emulsions (W/O-Es). [2] When trace amounts of water is mixed in oil, it is also difficult to remove the water. Different types of O/W-Ms have been separated by filtration and absorption using systems containing various materials with specific structures and wettabilities. These materials are usually porous to facilitate liquid absorption, storage, and transportation.For filtration separation systems, hydrophilic materials that are oleophobic in subaquatic environments are used as filters to retain oil and allow water to pass through, [15][16][17] whereas oleophilic materials that are hydrophobic under oil are used as filters to repel water and enable oil to pass through. [18][19][20][21] For absorption separation systems, various oleophilic and hydrophobic materials are exploited to absorb oil from water. [22][23][24][25][26][27][28] Speed and efficiency are the most critical factors for separation systems, and are widely determined by the method of separation, the structures and performances of the separation materials, and the characteristics, ratios, and amounts of the O/W-Ms. It is also important to achieve continuous and largescale oil/water separation. [28][29][30] Although systems comprising novel materials and devices have been employed for the rapid and efficient separation of oil and water, the exploitation of separation materials still faces many practical challenges. These Separating oil and water remains a serious challenge because various oil/ water mixtures are generated in large quantities by industrial processes, unexpected accidents, and daily life. Various systems containing materials with specific structures and wettabilities have been investigated as possible solutions to this issue. As a sustainable biological material, wood and its derivatives have many advantageous properties for practical applications. The present review mainly focuses on recent progress in using wood-derived systems for sustainable oil/water separ...