The 23-year-old produced a Games record time of 52.27 seconds as she stormed home in the final 15 metres to overtake her former world record holding older sister and clinch her first individual Commonwealth Games gold.
"It's incredibly surprising. I don't know how it happened but I'm glad it did," said Bronte, who had mentioned after claiming silver behind Cate in the 50m freestyle she would not mind if the order was reversed every now and then.
"I definitely didn't think I was going to go that quick."
Cate Campbell, who along with the 50m freestyle had won the 50m butterfly and anchored the 4x100m relay team to a world record, clocked 52.69 seconds to edge ahead of Canada's Taylor Ruck, who won her seventh medal of the Games with the bronze.
"It's half a second off my best time so you have to be happy with that," Cate said. "I'm so thrilled for Bronte to get a massive win in front of a home crowd.
"It's never easy being the second Campbell, but she's number one now and I'm thrilled for her.
"It makes the pain of finishing second a bit sweeter."
Ruck, who despite winning just one gold in the 200m freestyle at the Games, again impressed in her swim for bronze and is arguably the swimmer of the meeting.
The 17-year-old has now joined Elaine Tanner, who won seven medals in the pool in Kingston in 1966, for the most medals by a Canadian at a single Commonwealth Games.
"I'm in awe. I didn't really expect to get all these medals so I'm really humbled," Ruck said.
"I'm just so humbled to be able to tie with Elaine. She's an amazing person and I look up to her a lot."
Ruck has the possibility of earning an eighth medal on the final day of competition in the pool on Tuesday if she is named in Canada's 4x100m medley relay team.
(Reporting by Greg Stutchbury; Editing by Christian Radnedge)
