This paper considers the problem of output-feedback control of stochastic nonlinear systems. A predictive controller is designed for which stability and feasibility (in a probabilistic sense) are guaranteed from an explicitly characterized region of attraction. The controller's performance is characterized by its risk of allowing destabilizing system behavior. Since the controller design relies on certain convergence properties of the state observer, a compatible stochastic high-gain type observer design is also presented. Finally, simulation results illustrating the efficacy of the design are presented.