<p>In recent decades, the rapid advancement of sensor technologies has revolutionized research in grassland ecosystems. A wide array of sensor technologies has significantly enhanced field-based studies, contributing to a deeper understanding of grassland conditions. This review examines the synergistic potential of integrating remote sensing (RS) with various sensor technologies, such as hyperspectral, multispectral, thermal, and electrochemical sensors, highlighting their crucial role in understanding field conditions. The bibliometric analysis shows the chronological change in the usage and purposes of various RS technologies. Additionally, integrating these technologies into digital platforms offers holistic solutions for grassland management, benefiting farmers and researchers alike. A key contribution of this review is the organization of the grassland sensor landscape into four complementary pillars—structural, spectral, quantum, and proximal/physiological—and their integration with remote sensing, model–data assimilation, and digital platforms. We also synthesize emerging quantum-based approaches (e.g., cosmic-ray neutron sensing, neutron probes, graphene quantum-dot devices) and discuss their practical relevance for grassland monitoring.</p>