Red/Green/Blue/White light-emitting diodes (R/G/B/WLEDs) based on colloidal quantum dots have a great opportunity for flexible large-area displays or energy-efficient light sources due to the ease of color tunability and cost-effective solution processibilty. However, QLEDs reported ever have not satisfied the requirements such as brightness and operation voltage for practicable usages. Here, we present bright and low-voltage driven R/G/B/White-QLEDs with an inverted device architecture. Dichromatic (blue & yellow), trichromatic (blue, green, & red), and tetrachromatic (blue, cyan, yellow, & red) white-QLEDs exhibiting luminance of 500 ~ 5,000 cd m-2 at an applied bias below 6 V have been accomplished with mixed QD active layers in an inverted device structure. In addition, practical applications of white-QLEDs such as traffic signals, display back-lights, and white illumination sources are exemplified. Our approaches and present results demonstrate remarkable progress in device performances of R/G/B/White-QLEDs and also provide reasonable guidelines for the practicable realization of R/G/B/White-QLEDs.