Nye Frankie Newman, 17, from Aldershot in Hampshire, died in the French capital on New Year's Day.
Speaking at the memorial in Guildford, his mother Debs Malone told the crowd of teenagers to carry his spirit "forever".
A minute's silence was held at the event, organised by the Brewman parkour group Mr Newman co-founded.
His friends took part in a "remembrance jam" afterwards.
Ms Malone, 49, said: "Can I ask you all, please carry Nye's spirit with you forever and always, and smile.
"I want you all to put your hand on your heart now and we are going to get down for my boy.
"Stay safe, stay brave, stay strong yeah? And be happy."
Alex Grubb, 18, who helped to organise the event, described the teenager as kind, caring and "very eccentric".
He said: "He had his own style, he wasn't like anyone else. He was a bit out there, very opinionated but very loving at the same time."
Organisers estimated about 200 people attended the memorial.
Before the event, Guildford council and Surrey Police had warned businesses to take "reasonable measures to prevent rooftop access".
But organiser Luke Stones, 16, said: "We have had made it clear people should not go on rooftops.
"If they go on rooftops, it's not parkour, that's another sport. Today, we are sticking to ground level."
He said rooftop running was more usually referred to as urbex, climbing or roof-topping.
Mr Stones said people had travelled from across Europe and Hong Kong, where Mr Newman visited in the summer.
He said organisers could not comment on Mr Newman's death, but confirmed he "was not participating in parkour" at the time of the accident.
Guildford council said it provided Portsmouth Road car park as a meeting place for the memorial, but not as a place for free-running.
A statement said: "By providing an area for the memorial event, the council does not condone or encourage parkour or free-running in our car parks, properties or anywhere else in the town or borough, whether it is at a low level or on rooftops."
Mr Stones defended the activity and said: "It is another form of exercise.
"It is a way to express your emotions through movement.
"When you're doing parkour you're at one with yourself, it's almost like a meditation."
The UK this year became the first country to officially recognise parkour as a sport.
Free-runners gathered to remember a parkour enthusiast who died in an accident on the Paris Metro.