Microgels, hydrogels fabricated in microscale via various methods, can be jammed, and the jammed state can be influenced by some factors such as volume fraction (Ø), pressure and temperature. Compared to bulk hydrogels, jammed microgels have distinct characteristics. Structures of jammed microgels, stable through a balance of effective forces applied to them, can be changed by application of forces or pressure, implying shear-thinnning properties. Additionally, the ability to maintain structures under a static condition and porous internal structures of them has been extensively exploited in researches. Additional materials can be involved in jammed microgels for additional features (e.g., conductivity), and overall mechanical properties can be also controlled. These characteristics have been used in diverse biological studies by developing them as injectable scaffolds, drug delivery vehicles and inks and support bath in 3D printing processes. In this review, jamming processes, characteristics of jammed microgels, fabrication methods of microgels and applications of jammed microgels are discussed to provide a comprehensive understanding of jammed microgels and promote their use in diverse researches.