The Melrose wheelchair racer, who holds the 200m world record, picked up speed in the middle phase to clock 16.53 and bag third place on the podium by a margin of 0.37 seconds.
It was a relief for the Scot after she finished fifth in the short sprint on debut at Rio 2016.
“To be able to call myself a bronze medallist knowing there were moments in the race I definitely could have done more and done better is huge for me,” said the 25-year-old.
“I know there are only three years to Paris and I know that I can get stronger.
“Coming fifth in Rio, coming third now, hopefully that trajectory continues to go up and up and up.
“I just didn't want to come fourth again. I'm up on the podium this time and I can't believe that I am, which is amazing.”
Kinghorn suffered a horrific accident while clearing snow on her family’s farm aged 14 that damaged her spinal cord.
Now she is one of the fastest women on two wheels on the track and surged to 100m T53 bronze in Tokyo – without her family but now with the Games medal she has always craved.
“The night I had my accident, I felt all my dreams had been shattered,” said the 25-year-old.
“My family took me to every sporting event and gave me every opportunity possible and I wouldn't be doing this without them.
“Them not being there is obviously really, really tough but I know they're having a massive party back home and I'm sure they're jumping around celebrating."
Meanwhile, Gordon Reid feels Covid isolation has actually loosened the shackles as he continued his wheelchair tennis singles title defence with a fine quarter-final win over Gustavo Fernandez.
The Scot continues to be restricted to training and playing in Tokyo after a member of the tennis team’s support staff tested positive, seemingly threatening his medal chances.
But the 29-year-old surged into the semi-finals, recovering from a slow start in a repeat of the Rio quarter-final to beat the Argentine fourth seed 7-5 3-6 6-1.
“The situation has just allowed me a little bit more freedom on court, when you feel that opportunity has been taken away, the fact that you’re even playing is a blessing,” he said.
“In a way it’s helped me, helped my mentality to enjoy the experience more.
“I still believe I’m an underdog here. I’m playing the world number one tomorrow on his own patch, he’s the favourite. I’m still an underdog and I’m loving it.”
In the singles, the reigning champion now faces world number one and home favourite Shingo Kunieda in a hotly-anticipated semi-final.
Reid is now guaranteed a chance to play for two Paralympic medals having reached the gold medal match in the men’s doubles alongside Alfie Hewett.
Scott McCowan will be back out at the boccia, this time alongside brother Jamie rather than against him, after narrowly missing out on a BC3 singles medal.
The 30-year old from Ayrshire was always behind in his bronze medal match with Australia's Daniel Michel as he seeks his first medal at his third Games.
"I’m devastated at the moment," he admitted.
"To have two chances at a medal and then not to get one, that's absolutely gutting.
"I’ll bounce back and start again in the pairs. We’ve got a really good chance in that for a medal.
"I'm playing some of my best boccia ever, I think we’re definitely one of the favourites to go all the way here and I'm confident.
"I love playing with Jamie, we have that relationship where a lot of the time we don’t even have to say anything. We know what each other is thinking, we are very similar in terms of our mindsets and our personalities.
"I'm just loving being here again. One of the wonderful things about boccia is it is truly about the sport. There’s a great camaraderie between the players. There’s not really any egos but that doesn't mean I don't want to win."
McCowan's team-mate David Smith claimed a thrilling gold in the BC1 individual event.
The Welshman came back from 2-0 down to beat Malaysia's Chew Wei Lun, winning a third Paralympic gold medal and retaining the title he won at Rio 2016.
At the pool, Andrew Mullen rounded off his third Paralympics with a placing of 13th in the 50m freestyle S5.
The Glasgow sprinter touched in 36.01, finishing seventh in a heat where the Paralympic record fell and missing out on a final place by 0.74 seconds.
"This has been a hard meet for everyone, but the attitude and mood within the team has always been incredibly upbeat and positive," he said.
Having started a family and completed a degree in the last year, Rebecca Redfern won silver in the 100m breaststroke SB13.
The 21-year-old repeated her Rio 2016 result and looked set for gold but was caught in the final metres by Germany's Elena Krawzow.
Elsewhere for ParalympicsGB there was success on the table tennis table as Will Bayley and Paul Karabardak secured at least silver in the class 6-7 team event.
Sue Bailey, competing at her sixth Games, secured bronze with Megan Shackleton in the women's 4-5 team.
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