Three-dimensional porous materials with superior hydrophobic/oleophilic properties hold considerable promise as absorbents for oil/water separation. However, it is still a challenge to produce high-efficiency oil absorbents on a large scale. A mild, widely applicable, cost-effective method to yield absorbents with excellent absorption performance is desired. Herein we report for the first time a facile and inexpensive combustion-assisted in situ carbon deposition method to fabricate effective absorbents using a commercially available sponge as a porous substrate. This prototype offers large-scale preparation of the target product. The obtained sponge exhibits excellent hydrophobicity, fire-resistance, compressibility, and self-cleaning properties, and can effectively separate oils from water even under harsh conditions. More importantly, the obtained sponge is demonstrated to have excellent oil recoverability and absorbent regenerability, being one of the most comprehensive oil absorbents. Moreover, this method is suitable for different types of porous substrates and will find widespread applications for the separation of oils from water.