Fluorescence imaging techniques involving chemical sensors are essential tools in many fields of science and technology because they enable the visualization of parameters which exhibit no intrinsic color or fluorescence, for example, oxygen, pH value, CO2, H2O2, Ca2+, or temperature, to name just a few. This Review aims to highlight the state of the art of fluorescence sensing and imaging, starting from a comprehensive overview of the basic functional principles of fluorescent probes (or indicators) and the design of sensor materials. The focus is directed towards the progress made in the development of multiple sensors and methods for their signal read out. Imaging methods involving optical sensors are applied in quite diverse scientific areas, such as medical research, aerodynamics, and marine research. The art of sensorship: Fluorescence imaging methods in combination with optical chemical sensors enable the visualization of flows on surfaces (see picture), temperature gradients, and the two‐dimensional distribution of certain chemical species (O2, H+, metal ions, H2O2) at an interface. This Review highlights the design of sensor materials, including nanoprobes, and the development of multiple sensors and their signal readout.