With the penetration of semiconductor lighting, GaN-based white-light-emitting diodes (WLEDs) with a high color-rendering index (CRI) and simultaneous high luminous efficiency (LE) are required, especially for high-quality indoor lighting. Here, by adopting metal nanoparticles (Ag and Au NPs) into hybridized color conversion material composed of broadband LuAG:Ce phosphor and narrowband CdSe/ZnS red quantum dots, we have fabricated AgAu-WLEDs with simultaneously increased LE (12% increment at 40 A/cm2) and CRI (maximum of 94.5), and decreased correlated color temperature (CCT, from CCT=6000 K to = 4800 K), compared with WLEDs without metal NPs. This improved performance of WLEDs is ascribed to increased color conversion efficiency brought from localized surface plasmon resonance and thus a strong resonant light scattering effect from the incorporated metal NPs. We believe the approach reported in this work will find its application in GaN WLEDs, thus advancing the development of high-efficiency and quality semiconductor lighting.