Ultrasound-responsive nanoparticles (URNs) enable spatiotemporal activation of immunomodulators that can remodel the tumor microenvironment and strengthen immune responses. This review summarizes how URNs enhance immune checkpoint blockade, vaccines, T cell therapies, cytokine delivery, and innate immune modulators, while synergizing with strategies such as oxygenation, extracellular matrix depletion, metabolic reprogramming, and phototherapy. By offering precise control and reduced systemic toxicity, URNs represent a promising platform for the rational design of next-generation cancer immunotherapies.