Embodiments of a combined overspeed and fuel stream selector system are provided. In an embodiment, the assembly includes a conduit network, a Discharge Select Valve (DSV), and a shutoff valve. The DSV is fluidly coupled to a primary fuel inlet, a secondary fuel inlet, and a primary fuel outlet included in the conduit network. The shutoff valve is fluidly coupled between the primary fuel inlet and the primary fuel outlet. In a standard operation mode, the shutoff valve is maintained in an open position, while fuel received at the primary fuel inlet is directed through the shutoff valve, through the DSV, and to the primary fuel inlet. Conversely, in a backup operation mode, the shutoff valve is closed to block fuel flow from the primary fuel inlet to the primary fuel outlet, while the DSV directs fuel flow received at the secondary fuel inlet to the primary fuel outlet.