A support and control device for circular knitting machines, designed to be mounted in a circular knitting machines equipped with a needle-holding unit, with a plurality of needles and with a corresponding plurality of selectors for such needles, the device comprising at least one support body equipped at least with: - a mounting portion configured so as to allow the device to be mounted to a supporting structure of a circular knitting machine; - a first seat configured so as to house selecting units for controlling the plurality of needle selectors of the knitting machine; - a second seat configured so as to house at least one cam for controlling the needles or the selectors of the knitting machine; wherein the device comprises: - selecting units for controlling the plurality of needle selectors, associated with said first seat; - at least one cam (30; 40) for controlling the needles or for controlling the selectors, associated with said second seat, wherein said first seat is directly obtained in or directly defined on said support body of the device, characterised in that said selecting units for controlling the plurality of needle selectors comprise a plurality of levers, each one being configured so as to interact with the butts of a respective plurality of needle selectors, and a corresponding plurality of piezoelectric actuators, each piezoelectric actuator being configured so as to selectively move the respective lever at least between a first position, in which, in use, the lever interacts with the butts of the respective plurality of selectors, and a second position, in which, in use, the lever does not interact with the butts of the respective plurality of selectors, and wherein said plurality of piezoelectric actuators is directly associated with or directly engages one or more surfaces of said first seat of the support body of the device. - a mounting portion configured so as to allow the device to be mounted to a supporting structure of a circular knitting machine; - a first seat configured so as to house selecting units for controlling the plurality of needle selectors of the knitting machine; - a second seat configured so as to house at least one cam for controlling the needles or the selectors of the knitting machine; - selecting units for controlling the plurality of needle selectors, associated with said first seat; - at least one cam (30; 40) for controlling the needles or for controlling the selectors, associated with said second seat, wherein said first seat is directly obtained in or directly defined on said support body of the device, characterised in that said selecting units for controlling the plurality of needle selectors comprise a plurality of levers, each one being configured so as to interact with the butts of a respective plurality of needle selectors, and a corresponding plurality of piezoelectric actuators, each piezoelectric actuator being configured so as to selectively move the respective lever at least between a first position, in which, in use, the lever interacts with the butts of the respective plurality of selectors, and a second position, in which, in use, the lever does not interact with the butts of the respective plurality of selectors, and wherein said plurality of piezoelectric actuators is directly associated with or directly engages one or more surfaces of said first seat of the support body of the device.