The procession, which kicked off shortly after 1pm, brought together people of all ages, from infants in prams to elderly participants using walking sticks.
"We believe this is a record in Swedish history for the number of organisations participating in a single climate demonstration," Hedvig Schylander, a climate policy expert at the Swedish Society for Nature Conservation, told the TT news agency.
"At 12.30 it looked like the protest would be underwhelming, but then the trickle of people coming into Vasaparken just became thicker and thicker until all the roads were full of people of holding banners and the park was overflowing with people. There were so many people that the organisers struggled to make space for the procession to begin. I think everyone, both the organisers who said they had initially hoped for only 10,000 people, and all those present were surprised at the turnout," said The Local's Richard Orange.
The demonstration was deliberately non-political, with the politicians who marched told not to march under their party banners.
Alongside environmental groups, the demonstration brought together trade unions, religious communities, researchers, dancers, and musicians. Some participants dressed up as clowns, children wore animal costumes, and folk musicians performed along the route. Several demonstrators had cycled all the way from southern Sweden, travelling for the entire week, while others arrived by train from as far north as Gällivare.
"An important, urgent issue supported by very nice people of all ages. Pretty good vibes all around," commented Erika, a reader of The Local.
Alexandra Drotz Ruh, a participant who attended with her daughter Billie, stressed the urgency of the moment.
"I think what lies ahead for us – and especially for future generations – is absolutely terrifying. We have to act," she said.
Among those representing the younger generation was 16-year-old Lily Kjellberg.
"As children, we might not be able to do much to save the climate at a parliamentary or global level, but I want to be here to show what we stand for and what we believe," she said.
Did you attend the demonstration? Let us know in the comments what it was like.