Formamidinium lead bromide (FAPbBr₃) perovskite nanocrystals (NCs) have attracted great attention due to their remarkable performances of low cost, high color purity and tunable band gap. However, in a typical FAPbBr₃ perovskite light-emitting diode(LED), PEDOT:PSS, with hygroscopic and acidic nature, serves as a hole injection layer (HIL), thus leading to the device stability to decrease seriously. Device stability is one critical issue that needs improving for future applications. Here in this study, the nickel oxide (NiO) film prepared by the solution method is adopted as the HIL of the FAPbBr₃ perovskite LED to substitute detrimental PEDOT:PSS. Compared with the control device with PEDOT:PSS HIL, the resulting LED based on NiO film has the operating lifetime twice as great as that based on the PEDOT:PSS film. For further enhancing the performance of FAPbBr₃ LED, two metal dopants (Cs and Li) are introduced to improve the hole injection capability of NiO film and the charge carriers’ balance of device. With Hall measurements, both NiO and Cs/Li-doped NiO demonstrate a full p-type semiconductor characteristic. Increasing the doping concentration in the film can increase the carrier concentration and reduce the carrier mobility. This decreased carrier mobility results from the increased scattering due to grain boundaries and impurity phases, seriously at high Cs/Li concentration. As a result, the device, based on the NiO film (doping 2 mol% Cs) shows the best performance with a maximum brightness value of 2970 cd/m², current efficiency of 43 cd/A and external quantum efficiency (EQE) of 11.0%, thus its efficiency is increased nearly by twice compared with that of the PEDOT:PSS-based device. The results pave the way for making highly efficient and stability perovskite LEDs based on FAPbBr₃ NCs.