The three-time world champion, from Aldridge, cut a sad figure after her second place in the S5 200m freestyle but was all smiles after surging to 100m gold in a new world record.
Five years ago she was told never to swim again and just a few months ago a recurring shoulder injury looked to have ended her dreams of Paralympic selection, just as happened before Rio.
But all good things eventually come to those who work as hard as Kearney, who is known as one of the most committed swimmers on the British team.
“It’s made everything worth it,” said the 24-year-old, who touched home in 1:14.39.
“I tried not to watch Rio because it made me upset, it was really frustrating seeing the races won in slower times than I’d produced the year before but at that point I never thought I’d swim again.
“It was a case of thinking my dream was over and that I’d never get to a Paralympics, so to get here now and win a gold medal is crazy.
“Three weeks ago I got to the point where my shoulder was getting worse every session and I couldn’t swim, it was too painful.
“I didn’t actually think I would make it out here, so the fact that I have and then gone and won is just insane.
“I was so disappointed with the silver medal in 200m, it feels pretty cool to be standing here with a gold one.”
Kearney’s achievement was praised by team-mate and five-time Paralympic champion Ellie Simmonds, as she started her Tokyo campaign with sixth place in the SM6 200m medley.
The pair went to school together with Simmonds, a double gold medallist as a 13-year old at the Beijing Games, just a few years older.
“I’m so pleased for Tulley,” she said.
“I know how hard she’s worked for this and how many tough times she’s had to go through - that’s absolutely brilliant.”
Kearney was watched back home by mum Amanda, who she moved in when shielding during lockdown, and father Nigel and step-mum Sally.
“There have been so many people that have played a massive role in my journey,” she added.
“My local swimming club, my mum getting me back into the sport after Rio, having to learn how to swim again, the clubs and the coaches.
“Everyone in that group that helped me feel confident enough to get back in and try and swim again and get to this level.
“But most importantly is the medical team – the physios, doctors – from the Paralympics GB and obviously my coach and British para-swimming physio Richard Barber who spent so many hours on me, getting me ready and getting my shoulder to the state it is now that I can compete.
“If it wasn’t for him I wouldn’t have made it to this point.”
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