The usage of the abundant solar energy has attracted significant interest in the recent years, and the photothermal absorber with a high energy conversion efficiency due to its broad solar absorption has become a key component in many solar-harvesting applications, such as solar-driven steam generation. In this work, a polycaprolactone nanofiber composite with incorporation of carbon nanotubes or carbon nanoparticles is introduced with an average absorptance of 0.94 and 0.93 in the wavelength of visible and near-infrared light, serving as an excellent broadband solar absorber. The refractive indices of the composite are determined using a Lorentz-Drude oscillator model based on the experimental transmittance spectra. The composite yields an ultrahigh solar absorptance that contributes to an interfacial evaporation rate of 2.00 kg m-2 h-1 and 1.95 kg m-2 h-1 for carbon nanotubes and nanoparticle composites, respectively. Compared with other nanofabrication methods, electrospinning has the advantages of simplicity, cost effectiveness, and high efficiency, and it enables scalable fabrication of nanostructured materials. This work sheds light on a low-cost and high-output fabrication method for a nanofiber photothermal absorber composed of a biocompatible and biodegradable polymer and carbon materials.