In recent years, noninvasive focused ultrasound stimulation (FUS), with the advantage of high spatial resolution and high penetration depth, has developed rapidly for modulating neuron activities in the brain. Gamma oscillations serve to synchronize neurons and play important roles in cortical information processing and cognitive function. However, how FUS modulates gamma oscillations in the rat hippocampus is not well understood. In this work, we characterized the interactions between the gamma amplitude and phases of the delta, theta, and alpha bands during FUS. Our results show that FUS can significantly modulate the extent of phase-locked gamma amplitude and phase–amplitude coupling of brain oscillations. In summary, FUS can modulate gamma oscillations in the rat hippocampus, indicating its potential as a powerful noninvasive method to interfere with brain rhythms for diagnostic and therapeutic purposes.