Hundreds of millions of birds, insects, and other organisms move through the atmosphere every day, exerting substantial impacts on human society. As ecological risks in the airspace become increasingly prominent, systematic monitoring of airborne organisms is urgently needed. Given the irreplaceable advantages of weather radar for wide-area, all-weather observations, this review first explains the scattering principles underlying radar detection of biological targets and summarizes the technical characteristics of radars operating at different frequency bands and with different scanning modes for monitoring airborne organisms. It then reviews biological-echo identification techniques and bird-insect classification methods based on radar variables and artificial intelligence. Applications of radar aeroecology are discussed in four major areas: large-scale migration research, ecological and environmental assessment, aviation safety, and biological hazard prevention and control. Europe and the United States have established bird-activity warning and migration-forecasting platforms based on operational weather-radar networks, while China has also developed a nationwide aeroecological monitoring system using its weather-radar network. Looking ahead, China should further improve its capacity for biological species identification, strengthen the aeroecological monitoring network, and promote cross-sector applications, thereby advancing radar aeroecology from academic research toward integrated decision support for airspace management, ecological governance, environmental assessment, public health, and related fields.