The Russian former champion proved she was firmly back among the best with a 6-2, 3-6, 6-4 over Petra Kvitova, avenging her defeat to the Czech in last year's Wimbledon final and setting up a title match with Victoria Azarenka.
The elated Sharapova, who raised both arms in triumph after the win, said it showed she could once again compete at the highest level after shoulder surgery in 2008 and a series of later injuries.
The 24-year-old Russian won the Australian Open in 2008, the last of her three grand slam titles, before the operation kept her off court for nine months.
"It means so much to be back in a grand slam final, a stage I have been to before a few years ago here," Sharapova said.
"It's nice to get that far again after losing quite early in the last couple of years. It means a lot to me.
"I played someone that's just had really great results and has beaten me the last couple of times. I just really wanted it today."
And Sharapova, who could also return to world number one if she lifts the trophy on Saturday, said there were times when she thought she may not be able to make it back to the top of the sport.
"As positive as I always try to be, you always question what you're doing, obviously, because sometimes things work out and sometimes they don't," she said.
"And especially just with the shoulder I think it was -- I knew some examples of some people that did not quite recover from surgery and that was a little frightening, but I really had no option.
"So it was either give it a go or not do anything about it. Of course it took a long time and it was a process, but it was just something that was in my steps that I had to go through. And I did."
Sharapova and Azarenka, her rival for the title, have played six times previously for three wins apiece, but two of Azarenka's victories have come in finals, Stanford in 2010 and Miami last year.
"She's a really, really good player and I haven't had great success against her in the last couple of events that we've played against each other," Sharapova said. "I'd really like to change that."
Sharapova conceded that she had served poorly at times against Kvitova with 10 double faults, but said she was pleased with how she had been able to save break points at crucial moments.
"I felt like in the important moments I had some really good serves, and in the games where I was down love-30 and 15-40, I hit some really good second serves.
"Obviously I would like to see that (double fault) number lower, but when you're playing an opponent that has a really good return, sometimes you go for it a little bit more."