Over the years, the oxidative ring enlargement of furfuryl alcohols, known as the Achmatowicz reaction, has been developed into a powerful and versatile synthetic tool for the preparation of 6-hydroxypyranones. This review provides a comprehensive collection of the various ways to perform Achmatowicz rearrangement reactions and explores the role of this ring-expansion process in contemporary organic synthesis. 1 Introduction 2 Classical Methods and Variants 3 Single-Electron-Transfer Oxidations 4 Metal-Catalyzed Ring Expansions 5 Photolytic Oxygenations 6 Enzymatic Transformations 7 Conclusions