It is a high-stakes bet for the former president, who is facing legal trouble on various fronts in Brazil -- notably for his alleged role in inciting supporters who rioted through the halls of power on January 8 in a failed bid to oust Lula, the veteran leftist who beat him in a divisive election in October.
It threatens to be a tense day in Brasilia, where authorities vowed to block supporters from holding a huge welcome rally at the airport.
Bolsonaro, 68, is set to start a new job next week as honorary president of his Liberal Party (PL), earning 41,600 reais (around $8,000) a month.
The ex-president (2019-2022), who recently rented a house in a gated community in Brasilia, has said he plans to criss-cross Brazil "doing politics" and "upholding the banner of conservatism."
But "I'm not going to lead any opposition," Bolsonaro told CNN Brasil as he prepared to board his flight.
"I'm going to participate with my party as someone with experience."
Return of 'the face of the right'
Authorities in Brasilia urged Bolsonaro supporters not to rally at the airport, saying police would be out in force to keep traffic flowing smoothly.
The Liberal Party appeared ready to keep the arrival low-key, saying Bolsonaro would travel from the airport to party headquarters, where his wife, Michelle, party president Valdemar Costa Neto and "other authorities" would be waiting to greet him in a closed-door event.
But hardline Bolsonaro backers have plans of their own.
There are viral calls on social media for supporters to flood the airport to welcome the man they call "Messiah" -- or "Messias," Bolsonaro's middle name.
Some supporters are planning to hold one of the ex-president's trademark motorcycle rallies, vowing: "Brasilia will come to a halt."
"Let's pave the way for Bolsonaro's return to the presidency," YouTube star-turned-Congressman Gustavo Gayer said in a video, calling for a massive turnout.
"Bolsonaro is the face of the right in Brazil," supporter Cassia Christina told AFP in Rio de Janeiro.
"His name revived the right wing and patriotism in this country," said the 32-year-old vendor.
The homecoming could reenergize the opposition, which has been weakened by Bolsonaro's self-imposed exile and the widespread backlash to the violence and destruction of the January 8 riots, when supporters trashed the presidential palace, Congress and the Supreme Court.
"We've had five months of a basically dismantled opposition. Now, Bolsonaro's return to Brazil looks set to unite the right," political analyst Jairo Nicolau of the Getulio Vargas Foundation told AFP.
"That could make a big difference. Lula will have to govern with a united opposition."
But Bolsonaro faces numerous legal woes.
They include no less than five Supreme Court investigations that could potentially send him to jail -- including for allegedly inciting the January 8 riots -- and a recent scandal over allegations he tried to illegally import and keep millions of dollars' worth of jewelry given to him and his wife by Saudi Arabia in 2019.
Police summoned Bolsonaro Wednesday to give a deposition in the Saudi jewels case on April 5, officials told AFP.
He also faces 16 cases before Brazil's Superior Electoral Tribunal (TSE), which could strip him of his right to run for office for eight years, taking him out of the 2026 presidential race.
Bolsonaro has admitted he could face trouble.
Assessing his odds at a meeting with Brazilian business leaders in the United States earlier this month, he acknowledged he could be declared ineligible to run for office.
"But they won't send me to prison, unless there's some kind of arbitrary decision," he said.