Positioning mechanisms are critical components in advanced optical systems, such as Earth observation telescopes. They are used to adjust the position of one or more optical elements to account for various factors, including thermal effects, settling due to launch or environmental loads, thermo-elastic deformations, or the need to compensate for spacecraft microvibrations or jitter.In this context, the paper presents the design, implementation, and testing of a tip/tilt positioning mechanism. The paper describes in detail the various components of the mechanism, which is driven by four multilayer piezoelectric actuators, each preloaded by a compliant mechanical amplifier. It then presents the finite element model that simulates the mechanical behavior of the mechanism, and the series of tests carried out on the prototype. The primary objective of this mechanism is to enable and control the precise movement of an optical payload in three degrees of freedom: a translation along its optical axis and two rotations about axes located on its optical surface.