It will be Halep's second consecutive Grand Slam final and her fourth overall attempt to win her first title in a major.
No. 3 seed Muguruza professed not to know that she could overtake current world No. 1 Simona Halep of Romania by winning the Thursday semifinal.
Half an hour later 1-0 had become 6-1 and the challenge of Muguruza, who would have taken over at the top of the rankings with victory, appeared to be fading fast.
After Halep's 6-1, 6-4 win, Muguruza said: "Her shots were very, very deep and very aggressive, constantly". Halep will also have to contend with the fact that once she makes it to the second week of slams, Muguruza comes alive.
Two-time major victor Kerber raced into a 4-0 lead in the first set before having to rely on a tiebreak to nudge her ahead. After sitting out almost a year because of surgery on her right foot in January 2017, she has soared up the rankings and now made it to her second major final in the past nine months.
"I will try my best", Halep told the crowd at Court Philippe Chatrier, "and hopefully I will be better than a year ago". I just went and searched for her in the training room.
England show their strengths and weaknesses against Nigeria
Southgate gave Everton's Jordan Pickford his third cap in Saturday's 2-1 friendly win over Nigeria at Wembley. Obviously there is a long way to go, but yeah, we've just got to do what we done today.
Keys made it to the semis with a straight-sets win over Kazakhstan's Yulia Putintseva while reigning US Open champion Stephens eased past Russia's Daria Kasatkina. "I would just call it a road".
I can only conclude that the market has grossly over-reacted to seeing Muguruza's beating of Sharapova yesterday afternoon, and made her a false favourite for this clash - Halep at [2.10] is today's recommendation.
"Another great opportunity on Saturday and I'm really looking forward to it", said Stephens, whose late father, John, was the 1988 NFL Offensive Rookie of the Year with the New England Patriots.
After her third-round win against Julia Goerges, Williams charged at Sharapova's book, questioning why it wasn't truthful - at least to her - and why Sharapova was so obsessed with her as a subject.
In the other men's quarter-final, number three Marin Cilic and number five Juan Martin del Potro were at 5-all in a first-set tie breaker when the match-up of past US Open champions was stopped. "I played again one of my best matches on clay". I'm not ever going to try to be a person that isn't nice, so that feels more authentic to me and, you know, I think I'm still doing okay.
But by the third set Halep had broken the German's defenses - and her resolve - as she banged in 76 percent of her first serves, with only half the unforced errors of her opponent.
Muguruza eventually got on the board and started to settle into the second set, breaking serve and getting to within two games of a decider at 4-2.
"I think she's right now probably the best player". Ten-time champion Nadal completed a 4-6, 6-3, 6-2, 6-2 win over Diego Schwartzman.