The triple Olympic champion's bid for a 12th title in the event from the past 13 championships was foiled by fellow Queenslander Leiston Pickett, but second place was enough to ensure she will head to London to defend her Beijing gold.
"I did put a lot of pressure on myself, I'd done a lot of media in the leadup to say I was going to my fourth Olympics, so there was a fair bit of pressure on to make it and I've done that job tonight, I'm pretty stoked with that," the 26-year-old told reporters.
"I didn't think I'd ever make it to four Olympics, that's just an absolute dream."
Jones started poorly and posted a time of one minute, 7.64 seconds, nearly a second adrift of Pickett and more than two shy of her Australian record of 1:05.09, a result she blamed in part on illness.
"The time was pretty ordinary but I'm not too bothered with that at the moment ... It was apparently a bit of a viral thing going around that makes you really dizzy, and vomiting and diarrhoea and stuff. Not very nice.
"If I can come out and do 1:07 and still make the team and I'm not feeling 100 percent, that gives me a lot of confidence going into training."
Jones and Pickett are likely to clash for gold in London with American rival Rebecca Soni, who denied Jones the world title in Shanghai last year.
Jones's achievement brought some cheer back to the South Australia Aquatic and Leisure Centre following the colossal disappointment of Ian Thorpe failing to make the final of the 200 freestyle on Friday.
In the five-time Olympic champion's absence, Thomas Fraser-Holmes emerged triumphant, winning a thrilling duel with Kenrick Monk.
The 20-year-old Fraser-Holmes's title followed his 400 individual medley win on the opening day, while Monk's Olympic qualification was redemption of sorts after he was embroiled in scandal for lying to police about a skateboard injury last year.
"I did have my ups and downs and it was a bit of a roller coaster (but) I'm on the team and I'm going to London," Monk said.
Olympic silver medallist Hayden Stoeckel qualified for his second Games after edging Dani Arnamnart for the 100 backstroke title, while Emily Seebohm, who won gold in the 100 medley relay at Beijing, beat Belinda Hocking to win the women's event.
Stephanie Rice, swimming through the pain of a nagging shoulder injury, eased into the finals of the 200 freestyle and the 200 individual medley, raising hopes of defending all three of her Beijing Olympic titles.
World record holder Rice became the first swimmer to book her Olympic ticket at the trials when she won the 400 metres IM on the opening day on Thursday and will also hope to defend her 200 IM and 200 freestyle relay titles at London.
Controversial swimmer Nick D'Arcy qualified first into the 200 butterfly final to boost his London hopes, four years after being kicked off the Beijing-bound Olympic team for punching fellow swimmer Simon Cowley at a Sydney night club.
D'Arcy was convicted for assault and later filed for bankruptcy after he was ordered to pay A$180,000 in damages to Cowley. He was cleared to compete at the trials last month.
"I'm just trying to focus on each race at a time," D'Arcy said after his morning preliminary. "It's three rounds of a title fight."
Day four of the trials on Sunday will see Thorpe attempt to qualify for the 100 freestyle final - his last-chance saloon for London - in an ultra-competitive field including world champion James Magnussen and the other members of Australia's gold-medal winning 100 freestyle relay team.