AbstractARIES-ST is a 1000 MW fusion power plant conceptual design based on a low aspect ratio ‘spherical torus’ (ST) plasma. The power core uses an advanced ‘dual-cooled’ breeding blanket with flowing PbLi breeder and He-cooled ferritic steel structures. The main features of the blanket design are summarized here together with analysis of the thermal hydraulic and thermomechanical performance.