The verdict will bring to an end a 10-year probe into Indonesia’s deadliest act of terror.
Patek, 45, is accused of assembling explosives for twin suicide bombings on a bar and a nightclub in Bali that killed 202 people, including 88 Australians, and church attacks in Jakarta on Christmas Eve in 2000 that killed 19.
Patek will likely be spared the maximum penalty – death by firing squad – with prosecutors seeking a life sentence because the accused has shown remorse during the four-month trial.
Patek, dubbed “Demolition Man” by local media, is the last suspect detained in Indonesia to be tried over the Bali attacks that killed mostly foreigners.
The attacks triggered a long crackdown on terrorism in Indonesia, focused on weakening the al-Qaida-linked Jemaah Islamiyah (JI) terror network responsible for the bombings.
Anti-terror squads trained by Australian and US police have conducted raids and killed three suspects in the bombings: alleged masterminds Dulmatin and Noordin Mohammed Top, and Malaysian Azahari Husin, an alleged bombmaker.
Indonesia also executed three men in 2008 – Imam Samudra, and brothers Amrozi bin Nurhasyim and Ali Ghufron, known as Mukhlas – for playing major roles on the ground in the attacks.
Several others have been jailed, including bombmaker Ali Imron, who was given a life sentence for helping build and deliver bombs.
The only suspect yet to be tried is Riduan Isamuddin, known as Hambali, who allegedly helped orchestrate the attacks and has been detained at the US naval base at Guantanamo Bay since 2006, accused of having financial links to al-Qaida.
After more than eight years on the run, Patek was arrested in January 2011 in the Pakistani town of Abbottabad, where US commandos four months later killed al-Qaida chief Osama bin Laden in a raid.
Prior to his arrest, he was the most-wanted terror suspect in Indonesia and the United States had a $US1 million ($980,000) bounty on his head under its Rewards for Justice program.
Patek is charged with six offences, including premeditated murder, illegal firearms possession and bombmaking, but cannot be charged for the attacks under the country’s terrorism laws, which were implemented in 2003.
During the four-month trial, Patek has given emotional testimony, claiming he was “against it from the start” and that he tried to stop the attack at the 11th hour. He has also apologised.
“I regret what I have done… I apologise to the families of victims who died – Indonesians and foreigners,” Patek told the West Jakarta district court last month.
“I apologise also to victims who were injured.”
Patek has insisted he played a minor role in assembling the explosives, saying he mixed only 50 kilograms of chemicals out of a tonne.
But he admits attending a mujahideen camp on the Pakistan-Afghanistan border. US FBI special agent Frank Pellegrino testified he was a well-known expert bombmaker among militants in the region.
Mr Pellegrino said the FBI had collected evidence that Patek planned to kill US troops and suggested he went to Abbottabad to meet bin Laden before his arrest, a claim Patek has repeatedly denied.
More links with al-Qaida have emerged during the trial, with jailed Imron testifying in March that bin Laden provided JI with $US30,000 to wage jihad in Southeast Asia before the Bali attacks.
Prosecutor Bambang Suharyadi said last month that the Patek verdict will close the chapter of the Bali bombings and that “Indonesians and the international community have long waited for this case to be over.”
Several Australian survivors of the bombings have recounted their harrowing experiences in trials over the years, some showing judges their scars from shrapnel wounds and burns, and others describing psychological trauma.