This study investigates the effects of non-thermal levels of 900 MHz radiofrequency electromagnetic field (RF-EMF) which is used in mobile phone technology on neurodevelopment and neural stem cell differentiation. In vivo in the rat, the effects of pre- and post-natal 0.08 and 0.4 W/kg exposure were assessed on the proteomic profile at PND postnatal day 0 (PND) and on proliferation, synaptogenesis, and oxidative stress in the hippocampus and primary motor cortex of rats at PND 8 and PND 17. Complementary Mechanistic endpoints on cell differentiation were studied in vitro using stem cells exposed to 900 MHz RF-EMF at a non-thermal level for 3 or 7 days in vitro at the lowest SAR (0.08 W/kg). Our in vivo results showed a decrease in BDNF level and cells proliferation with a decrease in synapses balance. Increased proliferation, apoptosis, and double-strand DNA breaks in neural stem cells (NSCs) were also observed. Smaller ratio of B1 cells and a higher ratio of oligodendrocyte progenitor cells and astrocytes were observed in the exposed NSPCs. These findings suggest that developmental RF-EMF exposure induce changes in neurodevelopment in vivo from PND 0 and until PND 17 specifically on cellular proliferation supported by alterations in NSPCs in vitro, leading to the hypothesis of a vulnerability of developing central nervous system towards RF-EMF exposures at regulatory thresholds.