The Thai Royal Household Bureau announced that His Majesty passed away at 3:52 pm at the age of 89.
His Majesty has been hospitalised for years.
The bureau said in the statement that His Majesty has been admitted to the Siriraj Hospital since October 3 2014 and the doctors have been providing treatment to His Majesty to their full efforts.
"But His Majesty’s condition gradually worsened until His Majesty passed away at 3:52 pm at the Siriraj Hospital peacefully. He was 89 years and has been on the throne for 70 years.
Thai Prime Minister Prayut Chan-o-cha announced on Thursday that the Heir to the Throne will succeed His Majesty the King after his death.
"The government will proceed with the succession. The government will inform the National Legislative Assembly that His Majesty the King appointed his heir on Dec 28, 1972," Prayut
said in a statement broadcast on all television channels.
His Royal Highness Crown Prince Maha Vajiralongkorn was appointed the Crown Prince.
The PM’s Office announced that government agencies nationwide were ordered to fly half-mast for 30 days following His Majesty the King’s death.
The statement said government officials will wear black in mourning for a year. — The Nation/ANN