The 24-year-old from Coventry beat Switzerland’s Fabienne Kocher by ippon.
An early scoring waza-ari gave Giles the advantage and she showed the greater composure to secure success.
“It feels so special to do it in Japan. I believed I could do it, my coach has always believed I could and it showed in today’s performance,” she said.
“I felt really good in the warm-up, and I was taking each fight as it came. It’s an amazing arena and the atmosphere was amazing. To do it where Japan started it, it makes it extra special.
“I never underestimate any of my fights, that’s where mistakes are made. I go into the fight knowing what they do, and knowing what I’m capable of doing. With my best performance, I know I can beat some of the top players and today showed that.”
Giles had lost to eventual gold medallist Japan’s Uta Abe in the quarter-finals, but beat Charline van Snick of Belgium in the repechage to give herself a medal chance.
