This case-control study in Mexico City (2017–2022) evaluated residential ELF-MF and device-use proxies for RF exposure in relation to childhood CNS tumor risk. Elevated residential ELF-MF (≥0.4 μT) was associated with approximately doubled odds of CNST, while cell phone use showed no association. Prolonged tablet use, with or without internet connectivity, was reported to be associated with higher CNST risk.