As a new concept, a self‐crosslink mechanism for hydrothermal synthesis of poly(vinyl alcohol) (PVA) aerogel, assisted by multiwall carbon nanotubes, is reported. PVA, working as a low‐cost and commercially available raw material, exempts the complicated synthesis process and reserves its nontoxic nature since no organic crosslinkers are used in the synthesis process. The crosslink density and many other properties of the products can be easily tuned by simply altering the concentration of PVA precursors, which is considered to be another feature of our method. Dehydration between hydroxyl groups occurs in the hydrothermal process, leading to a reverse wettability of the products from hydrophilic to hydrophobic, thus their absorbing capacity for several organic solvents, such as bean oil and crude oil, is investigated. The absorbate has 10–52 times the original weight of the aerogel. As exhibited by the cytotoxic tests, the product has neglectable toxicity, suitable for application in environmental bioengineering. Furthermore, the product can be used as a facile substrate for transformation into conductive aerogel by in situ hybridizing with polypyrrole, showing a conductivity of 0.16 S m−1. As it is rich in hydroxyl groups, the aerogels are believed to be further functionalized by the reactions related to the hydroxyl group. A self‐crosslink mechanism for one‐pot synthesis of poly(vinyl alcohol)‐based aerogel is reported. No organic crosslinkers are required in the synthesis process and the raw material is low‐cost and commercially available. The products have good absorbing capacity for oil–water separation and meanwhile work as a “substrate” for in situ fabrication of conductive gel by hybridizing with polypyrrole.