The first bombs detonated almost simultaneously at around 6 p.m. in different parts of the city. At Victory Monument, a device hidden in a bus-stop shelter killed two people and injured seventeen, including a Hungarian tourist. In Khlong Toei, near Na Ranong intersection, a bomb concealed in a litter bin near a Chinese spirit shrine injured three people, including a ten-year-old girl; a sixty-one-year-old man died later at the hospital. The blast triggered a secondary explosion of propane gas cylinders standing nearby. Bangkok Governor Apirak Kosayothin led an early New Year's countdown at CentralWorld, then told the crowd to go home. After midnight, two more bombs detonated near CentralWorld itself. At a seafood restaurant near Pratunam Pier, a tourist had a leg blown off. The total toll: three dead, more than thirty-eight injured, and an entire city's celebration destroyed.

At three bomb sites, investigators found the letters "IRK" written in marker in four places: on a pillar near Victory Monument, on phone booths near Gaysorn mall and Pratunam Pier, and near the BigC department store on Ratchadamri Road. The IRK was known as an Afghanistan-trained urban guerrilla unit, but Interior Minister Aree Wong-araya dismissed the possibility of foreign militant involvement. Senior junta leaders agreed the initials were likely planted to mislead investigators. Experts from the Department of Special Investigation noted the bombs' construction matched techniques used by southern insurgents, right down to the Casio digital watches used as timing mechanisms. Stainless steel back covers from Series 200 and 201 Casio watches were recovered from multiple sites. Yet the military government that had seized power just months earlier insisted the southern insurgency had nothing to do with the attacks.

Prime Minister Surayud Chulanont blamed what he called the "old power clique," a reference to deposed Prime Minister Thaksin Shinawatra and his allies. Thaksin's Thai Rak Thai party denied involvement and warned the junta not to make accusations without facts. Surayud later backtracked, admitting his claim "was just an intelligence analysis" based on no solid evidence. A public opinion poll by ABAC found that a majority of Bangkokians did not believe the junta's narrative. Only eleven percent said they had "full confidence" the government could handle the crisis. Meanwhile, a rival theory circulated that the junta itself had planted the bombs to justify tightening its grip. Junta leader Sonthi Boonyaratglin denied this on television, insisting he loved his people too much to do such a thing. The truth remained elusive, tangled in the competing interests of military factions, deposed politicians, and a southern insurgency that the government refused to acknowledge.

The aftermath transformed Bangkok's physical landscape. Six thousand military checkpoints appeared across the capital overnight. The governor ordered all fifty districts to collect their rubbish bins, stripping the city of the very objects that had concealed several of the bombs. Junta leader Sonthi Boonyaratglin cut short his hajj pilgrimage in Saudi Arabia and flew back to lead the crisis response. Foreign embassies issued travel warnings. The Stock Exchange of Thailand fell 3.2 percent when markets reopened, compounding losses from the capital controls the junta had imposed in December. The Bangkok Metropolitan Administration announced plans to spend 186 million baht on 1,628 closed-circuit television cameras, an infrastructure of surveillance that would reshape the city's public spaces for years to come.

On January 20, 2007, police arrested fifteen military officers and civilians under martial law provisions that allowed seven days of detention without charges. Among them was Lt. Col. Suchart Khadsungnone, an officer from junta leader Sonthi's own Lopburi-based Special Warfare Command. The junta was dissatisfied with the police investigation and announced a parallel inquiry, then quietly dropped it after the police chief presented evidence to junta leaders. Later forensic analysis strengthened the case that southern separatists had built the bombs, but the junta maintained they had been hired by political operatives in Bangkok. No one has ever been convicted. The bombings remain officially unsolved, a void at the center of one of Bangkok's darkest nights, where the absence of answers became its own kind of political weapon.