Karina Menzies, 32, was with her children on Cowbridge Road West in the city when she was struck by a van – which allegedly went on to injure more than a dozen others in different spots within half an hour.
Friends of the mother-of-two staged the informal tribute to her outside Ely fire station.
A 31-year-old man has been charged with her murder, as well as 13 counts of attempted murder, South Wales Police said last night.
The dead woman's brother Craig Menzies paid tribute to her as a heroine who had given her life to save her children. He said: "She was the world to me. She was my best friend. She was a lively, bubbly person.
"There's just so many good things you could say about her. We'll all be lost without her."
Ms Menzies' family issued a statement saying: "Karina was a lovely girl.
"She lived for her kids and her brothers and sisters and everything she did was for her family. She was a good friend to everyone and was well thought of in the community."
The 31-year-old man in custody, who police have not named, was also charged with four counts of assault occasioning actual bodily harm and dangerous driving.
He will appear at Cardiff Magistrates' Court today.
Senior investigating officer Detective Superintendent Paul Hurley said: "South Wales Police has been overwhelmed by the support we have received from the community.
"We wish to express our sincere thanks to the many people who have come forward to give information, provide witness accounts, and offer both CCTV and mobile phone footage of Friday's traumatic and tragic events.
"Our thoughts this evening, as they have been all weekend, are with the family of Karina Menzies."