Official commemorations of Bhumibol were organised at Bangkok's Siriraj Hospital, where he died, and at Government House and the ornate royal palace.
But many ordinary people showed their respects on the streets, at neighbourhood markets and temples, kneeling before orange-robed monks to perform a Buddhist merit-making ritual.
"You see his achievements on TV sometimes, but now that he has passed we are learning about so many other things he has done for the country," said Panicha Nuapho, 66, who traveled from a province 330 kilometres north of Bangkok to pay respects at Siriraj Hospital.
Outside the hospital, mourners clad in black offered alms to a long procession of Buddhist monks and several thousand packed its grounds, joining nurses and doctors in prayers as monks chanted over loudspeakers.
Also Read
Bhumibol's death at age 88 after a reign of seven decades sparked a national outpouring of grief and a year of mourning that will culminate with his cremation on October 26.
More than 12 million people, or nearly a fifth of Thailand's population, have visited the palace throne hall where the king's body has been kept for the past year.
That effort built an aura of divinity around Bhumibol, who was protected from criticism by draconian lese majeste laws, but the king was also genuinely adored for his charitable work, personal modesty and as a symbol of stability in a nation frequently rocked by political turmoil.
Thailand's military government has asked the public to observe 89 seconds of silence today at 3.52 PM, marking the official time of Bhumibol's death in what Thai culture emphasises was his 89th year.
His son, King Maha Vajiralongkorn Bodindradebayavarankun, knelt before a portrait of the late king and Queen Sirikit at Dusit Palace and is expected to preside over merit-making ceremonies today and tomorrow.
Many people flocked to the palace area and left flowers beneath a giant portrait of Bhumibol.
Prime Minister Prayuth Chan-ocha, the head of Thailand's ruling junta which seized power in a 2014 coup it was said was necessary to restore political stability, oversaw ceremonies at Government House.
Supporters of the law argue that the monarchy is a sacred pillar of Thai society and must be protected at all costs. Critics say the law is being used to silence dissent.
Disclaimer: No Business Standard Journalist was involved in creation of this content