Rotating technologies, also known as HiGee technologies, typically involve the application of high gravity fields, of the order of 100–1000g, in order to intensify the fluid dynamics, mixing and heat/mass transfer in processing fluids. Research into such technologies for bioprocessing applications has a long history, with much progress achieved in a number of relevant applications from wastewater treatment to production of value-added chemicals such as bioethanol, citric acid etc. for the food, fuel and pharma industries. This chapter reviews the progress made in developing and applying rotating reactors for bioprocessing, focusing on whole cell fermentation and biotransformations. A background to bioreactor design requirements is first introduced followed by general considerations of rotating reactor concepts. Four configurations/modes of operation of rotating bioreactor designs are presented and discussed: the rotating fluidised bed, the rotating bed bioreactor, the rotating biofilm contactor and the rotating membrane reactor. Examples of industrially-relevant applications for each are also highlighted.