Alzheimer’s disease (AD) is a neurodegenerative disorder that jeopardizes the lives of diagnosed patients at late stages. This study aimed to assess, for the first time, the efficiency of germanium dioxide nanoparticles (GeO2NPs) in mitigating AD at the in vivo level compared to cerium dioxide nanoparticles (CeO2NPs). Nanoparticles were synthesized using the co-precipitation method. Their antioxidant activity was tested. For the bio-assessment, rats were randomly assigned into four groups: AD + GeO2NPs, AD + CeO2NPs, AD, and control. Serum and brain tau protein, phosphorylated tau, neurogranin, amyloid β peptide 1-42, acetylcholinesterase, and monoamine oxidase levels were measured. Brain histopathological evaluation was conducted. Furthermore, nine AD-related microRNAs were quantified. Nanoparticles were spherical with diameters ranging from 12–27 nm. GeO2NPs exhibited a stronger antioxidant activity than CeO2NPs. Serum and tissue analyses revealed the regression of AD biomarkers to almost control values upon treatment using GeO2NPs. Histopathological observations strongly supported the biochemical outcomes. Then, miR-29a-3p was down-regulated in the GeO2NPs-treated group. This pre-clinical study substantiated the scientific evidence favoring the pharmacological application of GeO2NPs and CeO2NPs in AD treatment. Our study is the first report on the efficiency of GeO2NPs in managing AD. Further studies are needed to fully understand their mechanism of action.