The development of advanced materials relies on an innovative combination of two completely different materials. Loading quantum dots (QDs) into a three-dimensional (3D) network of hydrogels has proved to be a win-win strategy to enhance the synergy of the components. The resulting new QDs/hydrogel composites have a wide range of applications in important fields such as health, energy and environment. Herein, we review recent research progress of QDs/hydrogel composites. Synthetic strategies are classified into different categories according to the preparative sequence, a relatively more practical perspective, between the QDs and hydrogel. In addition, we summarize the latest applications of these nanocomposites (NCs) in the sensing field, with a focus on fluorescence sensing. We hope that this review can provide the reader with a comprehensive understanding on this composite system quickly so that they can choose the most suitable preparation method or sensing scheme based on actual conditions and requirements to obtain QDs/hydrogel composites with optimal performance.