This report reviews the thermally activated delayed fluorescence (TADF) displayed by fullerenes. From the analysis of the steady-state data, time-resolved data, or by a combination of both, it is possible to determine several important photophysical parameters of fullerenes. Herein we also cover the development of temperature and oxygen sensors based on the TADF effect exhibited by fullerene C(70). Despite the work already carried out, knowledge of the photophysics of fullerenes and derivatives is still incomplete, and much remains to be done in this area and in the improvement of sensor systems based on fullerenes.