A colloidal quantum dot light-emitting diode (QLED) is reported with substantially enhanced electroluminescence by embedding a thin layer of Ag nanoislands into hole transport layer. The maximum external quantum efficiency (EQE) of 7.1% achieved in the present work is the highest efficiency value reported for green-emitting QLEDs with a similar structure, which corresponds to 46% enhancement compared with the reference device. The relevant mechanisms enabling the EQE enhancement are associated with the near-field enhancement via an effective coupling between excitons of the quantum dot emitters and localized surface plasmons around Ag nano-islands, which are found to lead to good agreement between the simulation results and the experimental data, providing us with a useful insight important for plasmonic QLEDs. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.