The Alberta skip made an open draw to the button on the final stone of an extra end to defeat Manitoba's Chelsea Carey 6-5 in the semifinal on Saturday night.
Sweeting will face defending champion Rachel Homan's Canada squad in the final on Sunday night.
"It's huge," said Sweeting, who is playing in her second Scotties. "To be one game away from a dream come true like that, it feels really good."
It won't be easy. Homan is 12-0 in the tournament, including a 10-5 win over Alberta on Tuesday in the round robin.
"It's going to be a good game — close with lots of rocks in play," said Sweeting. "We'll try to get them drawing and hope the angles are in our favour. They're really good at the high, hard ones, so we have to watch out where our rocks are."
Alberta third Joanne Courtney said the key is to keep Homan's team from pulling out the three-or-four point ends they have used to roll over most opponents in the tournament.
"You can't afford to miss too many against them,"said Courtney. "They've scored a lot of big ends this week, so we have to be careful when they have hammer with what we leave around.
"They're really good at weight. Sometimes you think you put it in the right spot and they make a triple or something."
Courtney put her second shot straight through the house in the extra end, but Carey was unable to make her pay for the error.
"I knew she'd want that one back, but the button was still open and, as a skip, that's all you want," said Sweeting.
Sweeting, who finished fourth in the round-robin portion of the tournament, got to the semifinal with an 8-7 victory Saturday morning over Saskatchewan's Stefanie Lawton.
Carey, who will play in the bronze medal game against Lawton, was dismayed at a spotty performance.
"It's terrible, it sucks," she said, lamenting too many missed shots. "There were a bunch throughout the game.
"We fought the inch a bit. We played a great game (Friday against Homan) and didn't win, and played a not-great game today and didn't win. It's just not our week, I guess."
Manitoba emerged from the first five ends with a 2-1 lead, but neither team looked sharp.
After the break, Sweeting hit for two in the sixth to take the lead, then got another in the seventh when Carey's draw to the button ran long.
The next end, it was Sweeting who went long on a draw and Carey was able to score two.
Then Sweeting was a tad heavy on a hit in a bid for two and had to settle for one. She took a 5-4 lead, but gave Carey the hammer going into the 10th.
Carey left a draw short on her first rock, then drew for one to send it to an extra end.
In the third-versus fourth game, Lawton left draws well short in the seventh and eighth ends to allow Alberta to steal five points en route to an 8-7 victory.
The missed shots left her squad down 8-3 with two ends to play. They closed the gap at the end but the outcome was not in doubt.
The Saskatchewan skip looked devastated.
"I had great draw weight at the beginning of the game and I just seemed to lose it after the sixth end," the Saskatoon resident said. "Just two tough draws and I couldn't make it for the girls and I feel not so good about that."
Saskatchewan looked to have taken control with a steal of one in the fifth for a 3-1 lead, but things went south after the break.
Lawton missed a double takeout that gave Sweeting an easy two to tie it in the sixth.
Then Lawton left a draw short to give Alberta a steal of two in the seventh for its first lead of the game.
A crisp Sweeting double takeout in the eight left a crowd of Alberta stones in the house. Lawton tried to draw into them but a groan went up from the grandstands as she left it short again for a steal of three.
She rebounded with two in the ninth and Sweeting's rink played with fire in the 10th by letting Saskatchewan put stones in the house. But a Sweeting takeout with the last stone sealed the victory despite Saskatchewan's steal of two.
"The ice was great," said Lawton. "It was a little keener and straighter but nothing we couldn't adjust to.
"It was just a matter of making better shots."
Now she hopes to salvage something by taking third place.
"We're going to come out and play for that bronze medal because we'd be very proud to win that one," she said.
It is Lawton's third Scotties after appearances in 2005 and 2009, and all three times she lost in the 3-versus-4 game.
She finished third in round-robin play at 8-3 but lost to Yukon (2-9) in her last game Friday. Fourth-place Sweeting had lost 8-6 to Lawton in the round robin.