<p>Controlling bifurcation pathways in soft origami mechanisms is important for developing intelligent, reconfigurable systems. This work introduces a novel design strategy for magnetically actuated soft origami mechanisms with programmable bifurcation behaviour, enabling the realization of a single, predetermined bifurcation pathway under an external magnetic field. Unlike conventional trial-and-error methods, the proposed approach incorporates the bifurcation pathway directly into the design stage. A parameterized framework is developed to simultaneously optimize the remanent magnetization distribution and the external magnetic field according to the prescribed bifurcation pathway. We successfully designed a family of square-twist (ST) origami mechanisms, each programmed to follow one specific bifurcation pathway under magnetic actuation using this framework. The bifurcation behaviour of these prototypes is systematically validated through experiments, whose results demonstrate close agreement with the theoretical predictions. This work establishes a new paradigm for exploiting bifurcation phenomena in magnetically programmable origami systems, paving the way for advances in soft actuation, deployable devices, and adaptive structures.</p>