Cellular activity is defined by the precise spatiotemporal regulation of various components, such as ions, small molecules or proteins. Studying cell physiology consequently requires the optical recording of these processes, notably by using fluorescent biosensors. The recent developments of various fluorogenic systems greatly expanded the palette of reporters to be included in these sensors design. Fluorogenic reporters consist in a protein or RNA tag that can complex either an endogenous or a synthetic fluorogenic dye (socalled fluorogen). The intrinsic nature of these tags, along with the high tunability of their cognate chromophore provide interesting features such as far-red to near-infrared emission, oxygen independence or unprecedented color versatility. These engineered photoreceptors, self-labelling proteins, or non-covalent aptamers and protein-tags were rapidly identified as promising reporters to observe biological events. This review focuses on the new perspectives they offer to design unique and innovative biosensors, thus pushing the boundaries of cellular imaging.