Early yesterday morning, Prime Minister General Prayut Chan-o-cha led an alms-giving ceremony with 161 monks in Sanam Luang. He was joined by hundreds of people and government officials. After that, the premier and his wife went to the Grand Palace to sign birthday messages for the Princess.
Similar events were held across the country, attracting a huge turnout of people - most of them wearing shades of purple.
In Ranong province, for instance, more than 500 people wore purple and rode their bicycles around a 5-kilometre route to mark the Princess' birthday.
"We have also held an alms-giving ritual, a reading event and a candle-lighting ceremony," Ranong Governor Suriyan Kanjanasilp said.
The United States Embassy in Bangkok also joined in by posting photographs on Facebook of staff wearing purple and a message that read: "On behalf of the American and Thai community of the US Mission to Thailand, the Embassy of the United States and the US Consulate General in Chiang Mai join the people of the Kingdom of Thailand in extending our best wishes to Her Royal Highness Princess Maha Chakri Sirindhorn on the occasion of her auspicious fifth-cycle birthday anniversary.
"We celebrate her inspirational and enduring work for the people and nation of Thailand, and her many contributions to Thai-American friendship, and wish Her Royal Highness continued health, happiness, and prosperity".
While presiding over a conference, Education Minister Narong Pipatanasai described the Princess as a great teacher.
"She has taught at the Chulachomklao Royal Military Academy [CRMA] for more than 30 years. She has also taken care of Chitralada and many other schools," he said, adding that the Princess often visited many schools in remote areas.
Meanwhile, at another event, Deputy Defence Minister General Udomdej Sitabutr, who is also Army chief, said the Princess had helped CRMA students and alumni become aware of their duties to society and the nation.
"Her work reflects her compassion and kindness, and Thais recognise this with their hearts," Udomdej said.
The Army held many activities to make merit in honour of the Princess, including organising blood donations and rescuing cattle from the slaughterhouse.