A system and method for forming a composite filler. The method comprises applying a pressure to a first portion of a composite material blank with a pair of forming dies of a composite filler forming apparatus, the pair of forming dies having a pair of convex radii, each forming die of the pair of forming dies having a respective convex radius of the pair of convex radii. The method also repeats the applying step to a subsequent portion of the composite material blank to incrementally form the composite material blank into a desired cross-section along its length.