"These are the moments we train and we practise and prepare for," Barty told reporters. "You know, sitting down with my team late last year, it was one of the goals we set out that we wanted to go deep into slams, and I feel like that was the next step for me.
"It's amazing that it's happened in Australia," added Barty, who is seeking to become the first home champion since Chris O'Neil in 1978.
Barty, who played professional cricket before returning to tennis in 2016, tried to take the sting out of the game early on by sending backhand slices to Sharapova.
However, the five-times Grand Slam champion, who beat defending champion Caroline Wozniacki in her previous match, looked in control, and after converting her third breakpoint in the ninth game followed it up with a service hold to love to take the opening set.
Barty fought back to break twice in the second set and level the match, as more unforced errors crept into her Russian opponent's game, and then broke twice more in the decider to race into a 4-0 lead.
Sharapova, the 2008 champion, rallied to win three straight games but could not prevent Barty closing out the match and becoming the first Australian woman to reach the quarters since Jelena Dokic in 2009.
Sharapova, who was suspended for 15 months for taking the banned drug meldonium in 2016, said Barty's style was difficult to play against.
"I thought she played a really great match, and I still had my chances which I didn't take," she said. "I definitely had a letdown for many games straight, gave her that confidence, and she's a confidence player, as well."
Barty will meet twice Wimbledon champion Petra Kvitova in the quarter-finals after the eighth seed thrashed American teenager Amanda Anisimova 6-2 6-1 earlier in the day.
The Australian lost her last meeting with Kvitova, in Sydney before the year's first Grand Slam.
"It doesn't get any easier at all, it's just another challenge and I'll try to come out and play my best tennis," said Barty.
"I think I love to play with freedom and fun and try and create as much variety as possible.
"Obviously my game is built around my serve and forehand and bringing in a variety with the slice. I think every day I try and challenge myself to add another string to my bow in a sense and try and become the complete player."
(Editing by Peter Rutherford)