The Australian's time at Brisbane's Chandler Aquatic Centre was two minutes 22.96 seconds, 0.03 seconds faster than the previous mark of 2:22.99 set by China's Hui Qi in 2001 and American Amanda Beard in 2003.
"That's quite a shock," 18-year-old Jones told reporters on Sunday.
"I can't begin to explain to you how much hard training we've been doing. It's hard to imagine what times are possible (in future).
"I'd like to see what I can do rested. To tell you the truth, it didn't even hurt that much.
"It was sort of one of those races where everything just happened. I just set my mind really clear, just really relaxed and just tried to hold it that way."
