The R1 relaxation rate of fat is a promising biomarker for mapping tissue oxygenation. Existing techniques to map fat R1 are limited to single-voxel or 2D imaging with long scan times. To address these limitations, this work presents a 3D technique to map fat R1 using a fat-water-separated variable flip angle (VFA) approach. The sensitivity of this technique to oxygenation variations was evaluated in a phantom. The results showed that fat R1 can be measured using a technique based on 3D VFA at 3 T and is feasible for MR-oximetry.