In this work, the effect of heat treatments on the anodizing behavior of additive manufactured AlSi10Mg material is studied. Specimens are subjected to artificial aging or stress release heat treatments, followed by galvanostatic anodizing in sulfuric acid. Optical and scanning electron microscopy are employed to study the microstructure and the oxide layer characteristics. Upon applying the heat treatments, the microstructure shows a gradual evolution from a continuous 3D silicon network toward separate coarse silicon particles in an aluminum matrix. The morphology of the silicon phase is found to be a deciding factor as it determines the fraction of silicon that is oxidized during anodizing. This in turn is found to have a direct impact on the anodizing efficiency and oxide layer uniformity. Thicker and more uniform oxide layers are obtained for the additive manufacture AlSi10Mg specimens after the silicon network is broken up due to the heat treatments.