King Bhumibol Adulyadej was admitted to the hospital in September 2009, while Queen Sirikit, 80, was treated for unusual heartbeat in 2012.
They are expected to arrive in Klai Kangwon Palace in the town of Hua Hin, a seaside town in the southern province of Prachuap Khiri Khan.
Prachuap Khiri Khan provincial governor Veera Sriwattanatrakul said about 10,000 people were expected to welcome the king and queen in Hua Hin, 192 kilometers south of Bangkok.