Julia Monaco, 26, was in a shopping mall with a friend when the van entered the crowded Las Ramblas.
“All of a sudden we were locked in the shop and confusion started to sprinkle among the people,” Ms Monaco told 3AW on Friday.
“The next second we knew we were literally running for our lives to the very back of the store where we were told to get on the ground away from the windows and lay as flat as possible.”
It's the third time Ms Monaco has been caught up in a terror attack since she left Australia three months ago.
“I was in lockdown on the tube the night of the London Bridge incident," she said.
“And I was also in Paris the day the incident took place at Notre Dame [where a man attacked a police officer with a hammer].”
Ms Monaco said there was “considerable panic” at the shopping mall and children were screaming, before police evacuated them through a side door.
“I feel a bit rattled; it’s not how I really expected today to go,” she said.
“But I don't feel like I want to go home. I feel like I want to stay here and not let them, whoever they might be, win.
“[I] still want to travel the world. Maybe there's something wrong with me, but I'm still going.”
Julia Monaco Source: 3AW