The present invention relates to a method for preparing a carbon nanofiber composite, and a carbon nanofiber composite prepared thereby. The method for preparing a carbon nanofiber composite provided by the present invention has reduced costs and is economical and efficient compared with a convention method for preparing a carbon nanofiber composite. In addition, the carbon nanofiber composite of the present invention can provide remarkable decomposition performance of organic pollutants, and a carbon nanofiber composite prepared by the preparation method of the present invention can be used in an electrode for an electric double-layer supercapacitor, a fuel cell electrode, a filter, a hydrogen storage material, and the like.