After building a 3-1 lead with a point for 4-1, Halep watched on as Stosur battled her way back into the first set, getting back on serve and pushing it to a tie-break. But the No.5-seeded Halep cruised through that breaker and the second set too, eventually closing out the No.7-seeded Stosur, 76(1) 62.
"It was nice, all the people who were supporting me, and supporting us - I want to thank them for all of their support," Halep said. "Maybe Sam was tired because she won in Osaka last week, and after Asia I had about 10 days of break because I had a right shoulder injury. But I recovered well from that, and now I feel good, and my game was very good this week. Maybe I was just a little bit fresher today."
Halep has been doing a lot of winning lately - this is her fifth WTA title of the year, having already won titles in Nürnberg, 's-Hertogenbosch, Budapest and New Haven. What's the key to her success?
"I've been playing more aggressively this year, hitting the ball very strong, and I'm more relaxed on the court and have been focusing much better on every point," Halep said. "I still have a few things I want to improve, but I will work on them in the off-season. I'm very happy with how I'm playing now.
"It's been an incredible year for me. I've won five titles now. I feel incredible."
Halep now has the second-most WTA titles ever for a Romanian, breaking a three-way tie at four WTA titles with Irina Spirlea and Ruxandra Dragomir-Ilie (she now trails only Virginia Ruzici, who won 11 WTA titles in her career, and who is Romania's only Grand Slam champion, at the 1978 French Open).
Only Serena Williams has more WTA titles than Halep this year - the American has won 10 of them.
Halep was asked afterwards about the Romanian women doing better than Romanian men as of late.
"Yes, we have a lot of girls in the Top 100," she said. "I don't know why. We are just fighting girls, we like to work a lot, and we like to play more tournaments than the boys. I can't say we don't have boys actually - in juniors they play well - but on the ATP World Tour not really. But I hope it will get better."
It was still a strong week for Stosur, who beat fellow Grand Slam champions Ana Ivanovic and Svetlana Kuznetsova in straight sets in the quarters and semis, extending her winning streak to nine matches in a row before finally falling to Halep. She was positive about the big picture, though.
"I think it was quite a battle to get to the tie-break in that first set - I was down 3-1 and got it back on serve, which was great," Stosur said. "But she really got on top of me in that tie-break, and from then on it was a real uphill battle. But all credit to her - she played solid the whole way through today.
"It's been a great couple of weeks. Of course you always want that little bit more, but today it wasn't meant to be, and there's lots to be happy about. It's been a great way to end the year, and now with Sofia coming up it's another chance to play Simona there. Obviously I'm in high spirits at the moment."
All was not lost for Stosur - later on she and Kuznetsova came back out on the court to win the doubles title, beating No.2 seeds Alla Kudryavtseva and Anastasia Rodionova in a match tie-break, 61 16 108.
It was Kuznetsova and Stosur's first WTA doubles title together - Kuznetsova, a former World No.3 in doubles, now has 16 WTA doubles titles to her name, while Stosur, a former No.1 in doubles, has 24.