Using first principles calculations we investigate the effect of external electric fields in the optical and electronic properties of blue-phosphorene nanoribbons. It is shown that the application of a static external electric field serves as a tool for controlling the band gap of blue-phosphorene nanoribbons. Accordingly, the system will show a transition from semiconductor to metal, depending on the intensity of the applied electric field and the width of the nanoribbon. Our results for the imaginary part of the dielectric function suggest that the optical properties of the blue-phosphorene nanoribbons can be modulated through of the electric field as well. © 2017 Elsevier B.V.