Turbulent fluctuations are omnipresent in the terrestrial magnetosphere as well as in other planetary plasma systems. While the topic is broad and was largely treated in the past (see, for instance, the works of Borovsky and Funsten, 2003; Zimbardo et al., 2010; Ovchinnikov and Antonova, 2017), this chapter provides a review that covers under the same title some key facts on the current understanding of turbulence observed in the main regions of the magnetosphere, such as the magnetosheath, the plasma sheet, and the cusps. We briefly discuss basic theoretical building blocks (mainly phenomenological) to set the scene for a discussion on the experimental results obtained during the last two decades of magnetospheric research. Indeed, an unprecedented fleet of spacecraft, like Cluster, THEMIS and MMS, provides in situ observations of magnetospheric turbulence for various geomagnetic conditions. We also discuss similarities and differences with respect to solar wind turbulence. In addition, we review ideas stemming from modern interpretations of turbulence and plasma and field fluctuations, such as dynamical complexity, and emphasize the key questions still awaiting clarification.