Many populations of long-distance migrant shorebirds are declining rapidly. Since the 1970s, the Lesser Yellowlegs (Tringa flavipes) has experienced a pronounced reduction in abundance by ~63%. The potential cause(s) of the species’ decline are complex and interrelated, yet understanding the timing of migration and seasonal routes used by this species will aid in direct conservation actions to address threats. During 2018–2021, we tracked 118 adult Lesser Yellowlegs using GPS satellite tags deployed on birds from seven breeding sites spanning the boreal forest of North America from southcentral Alaska to eastern Canada. Our objective was to provide the first comprehensive overview of Lesser Yellowlegs migratory patterns, including routes and timing, use of stopover and non-breeding sites, habitat associations, and migratory connectivity. Individuals tagged in Alaska and central Canada followed similar southbound migratory routes through the Prairie Pothole Region of North America, whereas birds tagged in eastern Canada completed multi-day transoceanic flights covering distances of >4,000 km across the Atlantic between North and South America. Upon reaching their non-breeding locations, Lesser Yellowlegs populations mixed, resulting in weak migratory connectivity. Lastly, agricultural and wetland habitats of the North American Prairie Potholes, the salt marshes of the Texas Gulf Coast, and the rangelands of the Argentine Pampas supported the highest proportion of Lesser Yellowlegs during southbound migration, northbound migration, and the non-breeding period, respectively. Our findings suggest that while Lesser Yellowlegs are exposed to a variety of threats throughout the annual cycle, the breeding population from which an individual originates influences which threats it experiences over its lifetime. Further, the species’ dependence on mixed agricultural and wetland landscapes during migration may make them vulnerable to threats related to agricultural practices (e.g., pesticides and habitat loss).