“Kirsty was loved and adored by her family, friends and boyfriend. She was the most outgoing, kind and generous person who loved to help people,” her family said in a statement confirming her death.
“As she ran towards danger, in an effort to help people on the bridge, Kirsty sadly lost her life.
“We are so proud of Kirsty’s brave actions which demonstrate how selfless, caring and heroic she was, not only on that night, but throughout all of her life.
“Kirsty – we love you and we will miss you dearly.”
It is unclear whether Ms Boden was attacked at London Bridge or during the rampage that followed in the Borough Market area.
South Australian Premier Jay Weatherill released a statement offering his “heartfelt condolences” to her family.
“This is a tragedy which will touch all South Australians,” he said.
“Kirsty’s death brings the horror of terrorism closer to home for all of us.”
A former teacher of Ms Boden called her a “beautiful girl, inside and out”.
“She was a beautiful girl inside and out. Very friendly, caring, always with a smile on her face. Just such a waste, such a waste of such a beautiful girl,” Jane Garrard told 9NEWS.
“Her parents can rightly be very proud of her. It does not surprise me that if there was a situation where someone else was in need that she wouldn’t jump in and do that at her own expense.”
Ms Boden had been living and working as a nurse in the UK while travelling in Europe and sharing her experiences online in a blog.
In one post she wrote: “at risk of sounding cliche, life is short and we should all use the time we have wisely”.
Meanwhile, fears are also growing for missing Brisbane woman Sara Zelenak, who became separated from friends at the scene of the attack.
A Facebook post by a family friend shared hundreds of times on Monday appealed for information about the 21-year-old, saying she usually rang her mother daily.