This oral talk will present an overview of principles and applications of quantum technology in geodesy and geophysics. Quantum technology impacts geodesy and geophysics in at least three major ways, quantum gravimetry in space and on ground, laser interferometry for gravity field missions, and relativistic geodesy with clocks. For example, precision navigation benefits from high-performance inertial sensors; timekeeping from frequency standards; gravity and gravity gradient measurements from cold atom sensors, on ground and in space. These and other applications will be highlighted in the talk.