Through density functional theory (DFT), we investigate the electronic and transport properties of zigzag phosphorene nanoribbons (ZPNRs) and armchair phosphorene nanoribbons (APNRs) passivated with only H or O, or both H and O with different arrangements, systematically. According to the calculated cohesive energies, all structures are stable. Also, the simulation results reveal a semiconductor-to-metal transition in zigzag groups, but all the APNRs are semiconductors. We see the direct-to-indirect energy bandgap transition in armchair groups, while all the semiconductors of zigzag groups have a direct energy bandgap. We also study the effect of external transverse electric field on electronic properties. The applying electric field changes the energy bandgap leading to a semiconductor-to-metal transition at a certain electric field. In addition, the direct-to-indirect bandgap transition and vice versa occurs for some samples. Moreover, edge passivation has a significant effect on transport properties. The breakdown voltage of the devices changes from 0 to 1.94 eV, and we observe negative differential resistance (NDR) for some devices. The results indicate that passivated phosphorene nanoribbons are possible, and their properties can effectively be tuned by the arrangement, type of edge atoms, and external electric field, which make these structures a promising candidate for feasible nanodevices.