A multistable compliant mechanism is a device that can hold several distinct positions through the storage and release of the strain energy associated with deflections of the flexible members. This self-locking capability can benefit many applications such as threshold acceleration sensing, overload protection, and shape reconfiguration. This work presents a novel class of fully compliant tristable mechanisms called tensural–compresural tristable mechanisms (TCTMs), which forms three stable equilibrium positions through unique utilization of both tensural segments and compresural segments. To identify feasible designs, a kinetostatic model is developed using the chained beam-constraint-model (CBCM) for both tensural segments and compresural segments. Two TCTM designs accompanied with a prototype are presented to demonstrate the feasibility of this new tristable configuration and the effectiveness of the kinetostatic model.