A system includes an exhaust diffuser system having an axial-radial diffuser and a transition duct. The axial-radial diffuser includes an inlet, an outlet, an axial diffuser portion between the inlet and the outlet, and a radial diffuser portion between the axial diffuser portion and the outlet, wherein the inlet is configured to couple to a gas turbine system. The transition duct is coupled to the axial-radial diffuser, wherein the outlet is disposed inside of an intake portion of the transition duct, and the transition duct includes a discharge portion configured to couple to a heat recovery steam generator (HRSG).