This study was conducted to determine the size of the breeding season home range and the migration pattern of Grey Heron (Ardea cinerea) using global positioning system telemetry in Daejeon, Republic of Korea. Four Grey Heron were successfully tracked between 15 March and 16 November 2016. The home range size for Grey Herons was estimated by minimum convex polygon (MCP) and kernel density estimation (KDE) of 90%, 70% and 50%. The mean home range size estimated by MCP varied among individuals, ranging from 14.3 to 1,372.1 km² (mean = 492.3 km²). The mean home range size using the kernel density estimation, which is indicative of the core area of a home range, was 114.2 km² (range = 1.8-352.2 km²). Of the four successfully tracked herons, two individuals stopped several times during their migration to the southern part of China. Further studies into habitat selection, seasonal patterns, and species-threatening factors would assist in the proper management of this species.