Carbon nanotubes (CNTs) were effectively dispersed and functionalized by being wrapped with RNA. The RNA-CNT hybrids attached strongly to an indium tin oxide (ITO) glass substrate and formed a uniform film, making it possible to use field emitters for field emission applications. An electron field emission cathode was fabricated with a spray method using these RNA-CNT hybrids. Well-defined RNA-CNT patterns were obtained on the ITO glass substrate. The cathode showed a uniform emission pattern across the entire surface and also exhibited a high current density. The RNA-CNT hybrids compared favorably to other factionalized CNTs for use in the spray method.