In one aspect, a rotor blade for a wind turbine may include a body extending between a root end and a tip end. The body may include a root portion extending from the root end. The root portion may include an inner surface defining an inner circumference. In addition, the rotor blade may include a root stiffener assembly disposed within the root portion of the body. The root stiffener assembly may include a plurality of stiffening ribs coupled to the root portion so as to extend along the inner surface. The stiffening ribs may be spaced apart from one another circumferentially around the inner circumference of the root portion