The Lindt Cafe reopened to the public at 10am local time, the same time when gunman Man Monis, a self-styled cleric, ordered the doors locked after taking 18 people, including two Indians, hostage inside the eatery in Martin Place.
During the dramatic events that unfolded on December 15, Monis made several demands, including that he be given a flag of the Islamic State group.
The siege ended after police stormed the cafe in the early hours of December 16 and killed Monis. Two hostages were also killed; one was killed by Monis while the other died after being hit by fragments of a police bullet.
Cafe worker Joel Herat, who survived the siege, was present inside the cafe when the doors opened, wearing his signature Lindt apron.
It will take a long time to adjust to the fact that it won't be cafe manager Tori Johnson greeting him at the door ahead of his morning shifts, Herat is quoted as saying.
"He was the first person who would come and greet me at the door, so that will take a long time to adjust to," he said.
"Working with these people here, it has helped a lot in the healing process."
A bouquet of flowers was tied to a flag pole outside the cafe with a note saying: "The light shines in the darkness and darkness has never put it out."
Two gold plaques have been placed at the cafe entrance, referring to the 38-year-old victim Katrina Dawson as "an inspiration" and the 34-year-old Johnson who will be "forever in their hearts".
New South Wales Premier Mike Baird, who visited the cafe on Friday, said there was a strong sense of camaraderie in the group.
He said the reopening was yet another "incredibly important step" for the city. "They are there because they believe in those who went through what they did."
"They are saying that they want to be strong for their friends, they want to be strong for this city and state."
Lindt Australia chief executive Steve Loane said the company was looking at the day as a "happy day".
He said counsellors would be on site for staff, if needed.
"That sadness doesn't go away but today is like a fresh start for a lot of us and, really, to get customers back in our store and see people smiling, and that's what we are about, is probably a fresh start for us," he said.

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