Color tunability of perovskite light emitting diodes (PeLEDs) by mixed halide compositional engineering is one of the primary intriguing characteristics of PeLEDs. However, mixed halide PeLEDs are often susceptible to color red-shifting caused by halide ion segregation. In this work, strongly quantum-confined perovskite nanowires (QPNWs) made of CsPbBr₃ are grown in nanoporous anodic alumina templates using a closed space sublimation (CSS) process. By tuning the pore size with atomic layer deposition (ALD), QPNWs with diameter of 6.6 nm to 2.8 nm have been successfully obtained, with continuous tunable photoluminescence emission color from green (512 nm) to pure blue (467 nm). To better understand the photo-physics of QPNWs, carrier dynamics and the benefit of alumina passivation are studied and discussed in detail. Eventually, PeLEDs using various diameters of CsPbBr₃ QPNWs are successfully fabricated with cyan color (492 nm) PeLEDs achieving a record high 7.1% EQE for all CsPbBr₃ based cyan color PeLEDs. And sky-blue (481 nm) and pure blue (467 nm) PeLEDs have also been successfully demonstrated, respectively. The work here demonstrates a unique approach to achieve quantum confined one-dimensional perovskite structures and color tunable PeLEDs, particularly blue PeLEDs.