Carbon aerogel (CASol-Ads) was prepared from waste corrugated cardboard (WCC) by using a green and facile strategy and it was explored as an all-in-one solar evaporator and a floatable absorbent. Thermal conversion of carbon precursor was investigated using thermogravimetric analyzer coupled with Fourier transform infrared spectrometer. The amorphous carbon aerogel was made up of criss-crossing carbon ribbons and it had a typical micromesoporous structure and a specific surface area of 575m2 g-1. It exhibited remarkable optical absorption over 81.8% in the UV and Vis regions and over 70% in the NIR region. The surface temperature of dry CASol-Ads can achieve 77.9 ℃ under 1 kW m-2 irradiation. The hydrophilic 3D network structure of CASol-Ads provides a large volume for the storage of liquids; thus, the carbon aerogel was able to store as much as 13.4 times its own weight in water. Solar-driven evaporation rate over CASol-Ads saturated with water was calculated to be 1.68 kg m-2 h-1, which was 4.5 times the value achieved with bare water under 1 kW m-2 irradiation. The adsorption behavior of CASol-Ads for methylene blue (MB) fitted the Langmuir isotherm model with the maximum monolayer adsorption capacity of 108mg g-1. The monolithic CASol-Ads can be used as a self-floating absorbent for the adsorption of MB from water, and the adsorption kinetics followed pseudo-second-order kinetics model.