Kim Phuc Phan Thi was only nine years old when she was photographed fleeing a napalm strike on her village in South Vietnam on June 8, 1972.
The image of her running naked down a road captured worldwide attention and later won a Pulitzer Prize.
She now lives in the Toronto area and spent much of the milestone looking back at how the iconic photo changed her life.
"I never thought that the child who was a famous symbol of war would one day be invited to become a symbol of peace," she told friends and relatives at an event marking the occasion.
"I have so much to be grateful for, but I did not make this journey alone," she said.
Joining her were Nick Ut, the award-winning photographer behind the image, and others who helped her survive the conflict, including doctors, nurses and even an immigration officer who helped her resettle in her adoptive country.
The event's organizer said the woman who garnered worldwide fame "can't even describe the emotions" stirred up by the anniversary.
"She would never have been alive if it wasn't for these people," said Liesa Cianchino, who is also a close friend of Kim Phuc's.
Cianchino said the date should always serve as a reminder of the atrocities of war and their impact on children.
Kim Phuc and her husband came to Canada in 1992.
Five years later, she founded the Kim Foundation International, which provides free medical assistance to children who are victims of war and terrorism.
She is also a goodwill ambassador for the United Nations Educational, Scientific and Cultural Organization, or UNESCO.