The Toronto native tied with Simone Manuel of the U.S. with a time of 52.70 to win the gold, becoming the first Canadian swimmer to win four medals in an Olympics.
“This is amazing, to tie for a gold. I never thought I’d win a gold,” Oleksiak said. “She (Manuel) deserves it as much as me. It means so much.”
The pair of swimmers also set an Olympic record with their tying time.
“My first gold medal, at my first Olympics, is kind of a surprise to me. I never thought I would be in this position but I’m so blessed and honoured to be on the medal stand,” the American said of her medal.
The Canadian Olympic Committee (COC) congratulated Oleksiak on her historic medal.
“Congratulations Penny on winning Canada’s first gold medal at Rio 2016 and for setting an Olympic Record,” COC president Tricia Smith said in a statement. “This is also the first time a Canadian has won four medals at a summer Games. Outstanding! Your performance was incredible and Canada is so proud of you.”
On Wednesday, Oleksiak anchored the women’s 4×200-metre freestyle relay team, where the 16-year-old and teammates Katerine Savard, Taylor Ruck and Brittany MacLean won the bronze medal.
Earlier this week, Oleksiak won silver in the 100-metre butterfly and bronze in the 4×100 relay.
She also set a Canadian and world junior record en route to qualifying for the women’s 100-metre freestyle finals.
WATCH: Penny Oleksiak’s brother plays hockey in the NHL, her sister is a NCAA rower, and now Penny is swimming for Canada in Rio. Penny is only 16 but in only a few years has proven she is a competitor who loves to win. Allison Vuchnich reports.
Also in the pool on Thursday, Kelowna, B.C. native Kierra Smith finished seventh in the women’s 200-metre breastroke.
Santo Condorelli didn’t qualify for the men’s 50 metre freestyle final. He finished fifth in his semifinal heat but a fast swim in the second semi bumped the Kenora, Ont., native to 12th.
Hilary Caldwell of White Rock, B.C., advanced to the final of the women’s 200-metre backstroke while Dominique Bouchard of North Bay, Ont., failed to advance to the final.
–with a file from The Canadian Press