It marks Gauff's first title at a WTA 1000 event - two weeks after she won in Washington for her first career WTA 500 title. At 19, she became the youngest woman to capture the title at the Cincinnati-area event.
Gauff, the number seven seed, took down world number one Iga Swiatek of Poland for the first time in eight attempts in Saturday's semifinal match before defeating Muchova, who is ranked 17th in the world.
"I'm really happy with how I was able to manage this week," Gauff said in her on-court interview after the match. "I got a huge win yesterday, a big one today.
"Karolina, she's not an easy player. It's really good to see her back at the top. I think she's one of the most talented players on tour."
On Sunday, Gauff won 35 of 50 first-service points (70 percent) and saved six of nine break points. She also broke Muchova's serve five times in eight opportunities.
"Today I really won it off of breaking serve, to be honest," Gauff said. "I wasn't really serving as good as I did against Iga. I don't know if it was nerves. I wasn't that nervous, to be honest. Also a combination of the long match yesterday. I wasn't serving as well.
"I think that's what makes a champion, is how you're doing on the days you aren't feeling so great. I'm glad I was able to push through."
Gauff won four of the final five games in the first set. Then she took a commanding 5-2 lead in the second set by breaking Muchova's serve twice. She failed to convert on three match points in the eighth game of the set but got it done in her next service game.
Muchova, the 2023 French Open runner-up, upset number two seed Aryna Sabalenka of Belarus on Saturday to advance to the final. She will crack the top 10 of the world rankings on Monday despite losing to Gauff.
"It's always a thing that is in your mind when you play tennis, to make it to Top 10," Muchova said. "It's happening for me tomorrow, so that's really nice result."
Tennis in the Land
Lin Zhu of China converted six of nine break-point opportunities to upset eighth seed Anna Blinkova of Russia 6-0, 6-3 on the first day of main-draw action in Cleveland.
The second set was tied 3-3 before Zhu won the final three matches, including a challenging eighth game where she rallied from down 15-40 to break Blinkova for the sixth and final time.
The opening round was easier for fourth seed Ekaterina Alexandrova of Russia, who defeated Romania's Patricia Maria Tig 6-1, 6-4. In the only other match of the day, Canada's Leylah Fernandez knocked off Czech foe Linda Noskova 6-0, 6-2 in just 64 minutes.
