Lambrecht's teammates Harm Vanhoucke, Tiesj Benoot, Jelle Vanendert, Victor Campenaerts and Sander Armee, as well as Arkea-Samsic's Andre Greipel, carried the coffin into the church of Saint Willibrordus in Knesselare where the ceremony took place.
"In Poland, we were sure about your victory and afterwards many more would follow," his mother Anje Lambrecht said while speaking to the congregation. "Of that we were sure. But unfortunately, fate decided otherwise.
"Why? Why you? Why aren't you here anymore? There is still so much to live for. I can't deal with this. I can't deal with this, Bjorg. I miss you. We miss you. The emptiness you leave behind is unbearable."
A giant screen on the wall of the church showed black and white photos of Lambrecht and a Lotto cycling jersey was placed on the coffin.
Lambrecht was one of Belgium's great cycling hopes. He won the under 23 Liege-Bastogne-Liege and finished second in the Tour de l'Avenir in 2017 behind this year's Tour de France winner Egan Bernal (Team Ineos) before turning professional last year with Lotto-Soudal.
This year he placed 12th at the Criterium du Dauphine, winning the best young rider category, fourth in La Fleche Wallonne and sixth at the Amstel Gold Race.
Lambrecht died on 5 August after crashing during the third stage of the race where he suffered severe internal injuries.
He was taken to hospital in a helicopter following the crash which occurred around 96 kilometres from the end of the Chorzow to Zabrze stage.