King Bhumibol Adulyadej of Thailand reigned for 70 years and 126 days, from 1946 until his death in 2016, making him the longest-reigning Thai monarch and, at the time, the world's longest-reigning living monarch and head of state. He remains one of the longest-reigning sovereigns in recorded history.
Record no. MRB-2026-005777
World's Longest-Reigning Monarch (at time of death)
Reference Record – Not Certified
This record is compiled from publicly available sources for reference. It has not been examined or certified by The Book of World Records.