Hierarchically uniform three-dimensional allium giganteum-like yttrium-based metal-organic framework architectures (Y-MOFs) have been successfully synthesized with use of polyvinylpyrrolidone (PVP) by a modified hydrothermal method. The allium giganteum-like architectures are made up of a large amount of nano-sheets. The morphology and grain size of the samples can be easily adjusted through the elaborate choice of reaction time and the content of PVP additives. A possible growth mechanism is proposed in detail. Under the UV light excitation, the Y-MOFs: xEu (x = 1, 2, 5, 10, 20, 50%) samples exhibit a strong red luminescence. The luminescence intensity increases first and then decreases with x value increasing, showing a maximum at x = 10%. Furthermore, the shape-preserved Y2O3:Eu3+ phosphors can be easily obtained via a heat-treating in the air using the corresponding MOFs as a precursor, which exhibit characteristic red emission and excellent thermal stability.