Tshisekedi's coffin was put on display for several hours in a large hall made available by city authorities, near the famous Atomium tourist attraction.
After a three-day funeral wake, Tshisekedi's coffin was put on display for several hours in a large hall made available by city authorities, near the famous Atomium tourist attraction, AFP journalists said.
Many waited in line for hours to get in and bow their heads in front of the casket, surrounded by wreaths of flowers and pictures of Tshisekedi, sporting his ever-present beret.
They came from across Belgium but also travelled from France, Britain and Germany, to pay a final tribute to "Tshishi", as his supporters called him.
"He is dead but his spirit remains among us. We will keep his heritage alive," one man told the crowd through a microphone, drawing applause in a hall filled with a festive atmosphere and many tearful eyes.
"He is our icon," added Armand Moke, who came from Dortmund in Germany. "He is a man who fought for some 30 years to establish democracy in our country."
Pelagie, 50 and from Antwerp in northern Belgium where she has lived for 10 years, added: "We have lost a real papa.
"He is a hero. What he did for Congo, nobody can do," she said, without hiding her concern. "Who is going to replace him?"
Tshisekedi died on Wednesday, having left the Democratic Republic of Congo eight days earlier for medical care abroad.
His death has plunged the vast African country further into uncertainty. He played a key role in negotiations aimed at peacefully resolving the political crisis triggered by President Joseph Kabila's refusal to leave power.
Kabila's mandate ended on December 20 but he has vowed to remain in office until elections can be held to choose a successor.
Tshisekedi became a dissident in 1979-1980 when he denounced the arbitrary rule of dictator Mobutu Sese Seko, whom he had supported in gaining power after the country's independence from Belgium in 1960.
He then led opposition to Laurent Kabila, who took office by force in 1997, followed by his son Joseph who became president after his father's assassination in 2001.
Beaten in 2011 elections tainted by massive irregularities, Tshisekedi refused to recognise Kabila's legitimacy to the very last.
"We invested a lot of hope in dialogue," said Jean-Pierre Mukendi, a Congolese who has been a priest in the Brabant Wallon region of central Belgium for 17 years.
"We told ourselves that we were nearly at the end of the tunnel," he said, while adding: "We are going through a time of uncertainty, but we remain hopeful."
DRCongo authorities have said they want to hold a funeral ceremony "befitting a former prime minister for Tshisekedi," although it is not yet known when his body will be transferred back to his homeland.