The far-right ex-army captain, who skipped town two days before Lula's inauguration on January 1, arrived back in Brasilia on a commercial flight from Orlando, Florida.
Scores of supporters waving the Brazilian flag -- one of Bolsonaro's symbols -- were at the airport arrival area to welcome him, shouting and singing the national anthem, despite authorities' moves to block a planned welcome rally.
"We've been waiting for this moment for a long time. We've been looking forward to it since January 1," Eva Melgaco, a 46-year-old beautician, told AFP.
However, Bolsonaro left discreetly through another exit. Flashing a thumbs-up to TV cameras, he entered a motorcade that headed for the headquarters of his Liberal Party (PL), flanked by police cars.
The homecoming is a high-stakes bet for Bolsonaro, who faces legal trouble on various fronts in Brazil -notably for his alleged role in inciting supporters who invaded 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.
Tension was high in Brasilia, where the exuberant crowd of around 200 supporters at the airport was guarded by a heavy police deployment.
Authorities said if necessary they were prepared to lock down the central plaza that is home to the presidential palace, Congress and the Supreme Court, where Bolsonaro backers rioted on January 8.
Bolsonaro, 68, is set to start a new job next week as honorary president of the Liberal Party, 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 crisscross 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.
"You don't have to oppose this government. It creates the opposition by itself."