Mr Basuki, better known by his Hakka Chinese name Ahok, was jailed in May 2017 after a Jakarta court found him guilty of blasphemy against Islam. He was sentenced to two years' jail but was released early after remission, totalling 3½ months, for good behaviour.
A number of Basuki supporters clad in red, blue and white shirts gathered outside the Mobile Brigade Detention Centre in Depok, South Jakarta, to wait for his release.
They chanted a national song adapted to cheer his freedom, saying "BTP is free, independent!"
The former governor recently asked supporters to refer to him as BTP instead of Ahok.
"Basuki Tjahaja Purnama got out of the (detention centre) around 7.30am," his secretary Ima Mahdiah said in a message to journalists. She added that he was picked up by his son Nicholas Sean and representatives of the "BTP team" - a group of close supporters who manage his social media accounts, among others.
Prior to his release, there were media reports and a lot of chatter online about his future.
His lawyer Teguh Samudera said on Tuesday that Mr Basuki has plans to get into the oil business in addition to hosting a TV show, Antara reported.
There is also talk that he will marry a police officer next month and that he is being invited to speak in several countries.
Mr Basuki's supporters went to the detention centre located on the outskirts of Jakarta despite his request that they refrain from doing so, to maintain order in the area.
Mr Ramjan Mohammad, sitting in a wheelchair, waited in front of the detention centre since 1am. He said he spent a few hours travelling from his relative's house in Jatinegara in East Jakarta by train and public buses to see his idol.
The 49-year-old said he had met Mr Basuki a few times before, and remembers how the former governor voiced his concerns for the rights of disabled people.
"I saw improvement of infrastructure and facilities for disabled people, especially in the transportation sector, during his leadership," he told The Straits Times.
He added that he had admired Mr Basuki's leadership and was grateful for the changes he introduced to the chaotic capital, such as cleaning up Jakarta's dirty rivers.
"People still need his thoughts," he said. "Maybe he can become a minister, especially communication minister because he likes talking," he said, laughing.
Another supporter, Ms Hesti Iriani, travelled hundreds of kilometres by train on Wednesday from her home town Yogyakarta to Depok to witness Mr Basuki's release.
"I really want to meet him. I want to support him, let him know he's not alone," she said.
The 50-year-old housewife, who wears a veil, said that Mr Basuki set an example of honesty and discipline which inspired not only other leaders, but also ordinary people.
On Mr Basuki's plan to set up an oil business and become a TV host, Ms Hesti said that it would be good for him, acknowledging that it may be hard for him to return to politics.
Meanwhile, his son Nicholas Sean posted on Instagram a photo of them together, saying: "He's back. My dad's a free man! Thank you everyone for the support."