The fabrication of superabsorbents for oil spillage cleanup is a hot topic today. However, the development of a low cost and highly efficient superabsorbent is still a big challenge. In this paper, we demonstrate a simple method to produce a low-cost, ultralight, elastic, and highly recyclable superabsorbent from renewable cellulose fibers via simple and environmentally friendly microfibrillation treatment and freeze-drying. Since microfibrillation of cellulose fibers resulted in hierarchical fibers that possess both fiber bulk and considerable microfibrils on the fiber surface, hierarchically porous sponges with ultralow density (0.0024 g cm⁻³) and high porosity (up to 99.84%) were obtained after freeze drying. The porous sponges after hydrophobic modification were elastic and exhibited rapid and outstanding absorption performances for various oils and organic solvents. The hydrophobic superabsorbent could selectively absorb oil from an oil–water mixture and showed an ultra-high absorption capacity of 88–228 g g⁻¹, which is comparable to those of other novel carbon-based superabsorbents. More importantly, the superabsorbent showed excellent flexibility and elasticity, and could be repeatedly squeezed without structure failure (more than 30 times). The absorbed oil could be readily and rapidly recovered by means of simple mechanical squeezing, while the superabsorbent could be reused at once without any other treatment. The superabsorbent showed excellent recyclability and could be reused for at least 30 cycles while still maintaining high oil absorption capacity (137 g g⁻¹ for pump oil). These advantages make the superabsorbent an ideal alternative for oil spillage cleaning.