The 14th-seeded Spaniard advanced to the final at the All England Club by beating Magdalena Rybarikova 6-1, 6-1 Thursday on Centre Court.
Muguruza reached the Wimbledon final in 2015, but lost to Serena Williams. She will get a second chance at the title on Saturday against either five-time champion Venus Williams or Johanna Konta.
"I lost two years ago," Muguruza said, "so I really look forward (to) this one to try to change that."
Muguruza won the first five games of the first set, facing only one break point and saving it. The 2016 French Open champion then broke Rybarikova twice to open the second set and take a 4-0 lead.
Muguruza, who is coached by 1994 Wimbledon champion Conchita Martinez, is now 3-0 in Grand Slam semifinal matches.
"I think she's helping me to deal with the stress of the tournament, because it's a long tournament," Muguruza said. "So she just knows how to prepare, how to train, what to do."
Rybarikova was playing in a major semifinal for the first time. At No. 87, she was the fourth lowest-ranked player in history to reach the Wimbledon semifinals.
But the unseeded Slovak entered Thursday's match with an 18-1 record on grass this season, including a run to the semifinals in Nottingham. She also won two lower-level events.
"I was a little bit nervous, a little bit tired also in my legs," Rybarikova said. "So I just have to be more relaxed maybe next time, if I would ever be again in semifinal, or to have such matches. I just have to be more relaxed and (have) more belief in myself."
The 23-year-old Muguruza, who is playing at Wimbledon for the fifth time, has dropped the least amount of games at this year's tournament, losing only 39 so far.
"Just went out there and didn't expect anything," Muguruza said. "Just expected myself to be ready as much as I could. Maybe the score did look maybe easier than actually playing during the games."
In the second match on Centre Court, Williams was looking to reach her ninth final at the All England Club - and first since 2009. The 10th-seeded American, who is 37 years old, is 8-1 in Wimbledon semifinal matches over 20 appearances at the grass-court major.
Konta was playing in the Wimbledon semifinals for the first time.
"I'll be ready no matter who is in front of me," Muguruza said. "I've learned a lot."