The Abu Rusheid A-type granite and Abu Ghalaga I-type tonalite in the Southern Eastern Desert (SED) of Egypt are a part of the Arabian-Nubian Shield (ANS), which was generated during the East African Orogeny. This study presents a multidisciplinary approach integrating field observations, petrography, mineral and whole-rock chemistry, and remote sensing data. The main objectives are to delineate the type and distribution of post-magmatic hydrothermal alteration, sources and mechanisms of fluid flow along shear zones, and metasomatic processes controlling mineralization in these particular granitic plutons and the ANS in general. Remote sensing, using Landsat-8 OLI, ASTER, and Sentinel-1A datasets, successfully identified structural controls of fluid flow, which has given rise to four hydrothermal alteration zones, including argillic, propylitic, phyllic, and gossan. The Najd Fault System, with an NW-SE trend and its conjugated NE-SW trends, served as primary conduits, which facilitated fluid circulation and subsequent metasomatism and post-magmatic hydrothermal alteration. The studied granitoids have undergone alkali metasomatism in the form of albitization, muscovitization, and argillic overprints. Abu Rusheid granites experienced extensive albitization (Na2O, up to 7 wt%; Na/K, 15) relative to Abu Ghalaga tonalite (Na2O, up to 5.6 wt%; Na/K, 16). Isocon analyses and mass-balance calculations indicate significant mobility of major and trace elements, driven primarily by albitization processes, including Na, Ca, K, Fe, Mg, P, Rb, Sr, and Zn. While the apparent ‘gains’ and losses of immobile elements (e.g., U, Zr, Hf, Nb, Ta, Y, Ti, and REE) between metasomatic fronts of the studied granitoids are probably due to dissolution of their host mineral phases such as biotite, zircon, garnet, columbite, and monazite, and cannot be related to albitization processes. The surface-derived fluids serve as albitizing agent in Abu Rusheid and Abu Ghalaga granitoids. However, magmatic-hydrothermal fluid overprint is clearly evidenced in Abu Rusheid granites through muscovitization (K2O, up to 7.0 wt%) associating albitization alongside the tetrad effect of highly to extremely albitized samples. Conversely, albitization in Abu Ghalaga tonalite is overprinted by argillic and propylitic alteration. Despite overprinting magmatic geochemical signatures by metasomatism, a set of least altered granitic samples, as well as preserved primary garnet and biotite retain primary igneous features, allowing inferences about their parental magma and tectonic setting. Abu Rusheid granites display geochemical signatures of peraluminous to alkaline crustal-derived magma (ASI ≈ 1.03-1.05) in a post-collisional extension setting, with high silica (SiO2 up to 77 wt%), elevated HFSE (e.g., Nb, Zr, and Hf), and REE (up to ~473 µg/g) contents, along with prominent negative Eu anomalies (av. Eu/Eu*= 0.002-0.04). On the other hand, Abu Ghalaga tonalite exhibits signatures of metaluminous to slightly peraluminous (ASI= 0.94-1.06), mantle-related magma in a volcanic arc environment, with moderate SiO2 (up to 67.88 wt%) and high CaO (up to 4.83 wt%) and Sr (up to ~334 µg/g) contents. The geochemical and remote sensing data suggest that fluid circulation along shear zones plays a crucial role in regional-scale metasomatism and the evolution of hydrothermal systems in the ANS. Understanding this system has broader implications for mineral exploration and tectonomagmatic models of the ANS.