Multicolor fluorescent polymeric hydrogels (MFPHs) are three‐dimensionally crosslinked hydrophilic polymer networks with tunable emission color. Different from the classic fluorescent materials that are used primarily in dry solid states or solutions, MFPHs exist as highly water‐swollen quasi‐solids. They thus present many promising properties of both solids and solution, including tissue‐like mechanical properties, an intrinsic soft and wet nature, fabulous biocompatibility, along with a responsive volume, shape, and fluorescence color change. These advantageous properties hold great potential in many applications such as sensing, bioimaging, information encoding, encryption, biomimetic actuators, and soft robotics. This Review gives an in‐depth overview of recent progress in the field of MFPHs, with a particular focus on the diverse construction methods and important demonstrated applications. Current challenges and future perspectives on MFPHs are also discussed. Multicolor fluorescent polymeric hydrogels (MFPHs), rising stars of luminescent materials, are the marriage of multicolor fluorescent materials and polymeric hydrogels. They have many extraordinary properties, such as a tissue‐like modulus, an intrinsic soft and wet nature, and fluorescence color change. In this Review, recent progress in MFPHs is summarized, with a particular focus on the construction methods and important applications.