The aim of this study was to develop nanofibers containing nanoparticles with potential for the biological fixation of CO together with the microalgae Chlorella fusca LEB 111. An electrospinning technique was used for the production of polymeric nanofibers with different concentrations of iron oxide nanoparticles: 0, 2, 4, 6, 8, and 10% (w v). Nanofibers with a nanoparticle concentration of 4% (w v) were selected for use in the microalgal cultivation due to their smaller diameter (434 nm), high specific surface area (13.8 m g) and higher CO adsorption capacity (164.2 mg g). The microalgae C. fusca LEB 111 presented a higher CO biofixation rate of 216.2 mg L d when cultivated with these nanofibers. The results demonstrated the potential of electrospun nanofibers as physical adsorbents of CO since they can increase the contact time between the gas and the microorganism and consequently increase the CO biofixation by the microalgae.