We report on a theoretical study of the giant magnetoresistance (GMR) effect in a δ-doped magnetically confined semiconductor heterostructure nanostructure (MCSHN), which can be realized by depositing two nanosized ferromagnetic (FM) stripes on top and bottom of the semiconductor heterostructure and using the atomic layer doping technique. It is shown that such a nanosystem shows up a sizable GMR effect due to a significant discrepancy in transmission of parallel (P) and antiparallel (AP) magnetization configurations. It is also shown that the MR ratio varies sensitively with the weight and/or position of the δ-doping. Thus, one can conveniently tailor the degree of GMR effect by tuning the δ-doping, and such a nanosystem can be employed as a controllable GMR device for magnetic information storage.