The Romanian, 26, won 6-1 6-4 against the Spanish third seed.
When Sloane Stephens's last service-return bid had struck the net, Halep finally had freed herself of whatever goblins had come and lurked from three prior Grand Slam finals that went both long and melancholy. She also was coming off a lopsided victory in the quarterfinals a day earlier, overwhelming Sharapova 6-2, 6-1. I will think that I will make many people happy.
The psychology of this final involved Halep desperately wanting to break her duck at the Majors and Stephens having the security of already knowing that she had one in the bank.
"It's Simona's third final in Roland Garros, she has a great level". Like previous year, I feel Halep will make an excellent start to the match but when it gets tight, she might just falter. But I love everything about Sloane Stephens' attitude when it comes to big matches, and I think it gives her the slightest of edges.
And though there was some brief drama when Keys conjured up a break of her own just as Stephens was serving for the match, it only served to delay the inevitable.
"I mean, there is no formula". So I have nothing to lose tomorrow.
- Juan Martin del Potro nearly didn't play in Paris due to injury, but will take on Rafael Nadal in the last four on Friday. You have to take a lot of risks. But nothing is impossible.
Muguruza, who won the title in 2016, will play top seed Simona Halep for a place in Saturday's final.
Ethical polluting agent: The toxic embarassment of Scott Pruitt
Democrats continue to call for Pruitt to resign amid the growing list of controversies. "Administrator Scott Pruitt , thank you. Senate Joni Ernst (R-IA) joined a chorus saying earlier this week: "He is about as swampy as you get here in Washington , D.C.
"I think it was still kind of a confusion in the head up until about a week ago (smiling)".
"It was someone who made a loud (noise) before my serve, and I made double fault".
"When you're writing an autobiography, I don't think there is any reason to write anything that's not true", Sharapova said. To have had the victories that I have had, to have the results that I have, obviously moving a step in the right direction. I'm just going to take it in stride and just enjoy it and go out and compete. I'm not trying to break a record.
- Del Potro explains why he became angry at a member of the crowd. Now I just have to go find her, because I need to tell her some juicy stuff.
"I don't know who said that I feel pressure".
There was no doubt entering Thursday's semifinals that there would be an American woman advancing to the final of the French Open.
9 - years since Del Potro last reached the semi-finals. After such a long wait, it feels like her time.
74 - unforced errors made by Marin Cilic in his quarter-final exit. Despite her first loss to Muguruza in their fourth meeting, committing 27 unforced errors and getting broken six times, Sharapova said she saw signs of hope in her form as she builds towards Wimbledon next month.