A giant magnetoresistance (GMR) magnetic head that includes a GMR read sensor with a stitched longitudinal bias (LB) stack. The GMR read sensor includes seed, pinning, pinned, spacer, sense and cap layers in a read region, and its seed and pinning layers are extended into two side regions. The LB stack is fabricated on the pinning layer in the two side regions and includes separation, seed and LB layers. The separation layer, preferably made of an amorphous film, separates the pinning layer from the seed and LB layers and thereby prevents unwanted crystalline effects of the pinning layer. Monolayer photoresist patterning and chemical mechanical polishing may be incorporated into the fabrication process of the GMR head to attain uniform thicknesses of the separation, seed and LB layers, and to align the midplane of the LB layer at the same horizontal level as the midplane of the sense layer.