Having not dropped a set throughout the tournament, Swiatek initially took a commanding lead, reaching 3-1 in the second set.However, Muchova mounted a comeback, winning four consecutive games and pushing the match into a deciding set.
Undeterred, the 22-year-old Polish player rallied and regained her composure just in time. She clinched the victory, capturing her fourth Grand Slam title overall, following her triumph at the US Open last year.
Swiatek has now lost only two out of 26 Grand Slam matches since moving to world number one in April last year and the 22-year-old became the youngest woman to bag consecutive trophies at Roland Garros since Monica Seles, who triumphed from 1990-92.
The US Open champion also joined Seles and Naomi Osaka as the only women in the Open Era to emerge victorious in each of their first four major finals but she was made to work hard despite a fast start.
Swiatek worked the angles superbly from the baseline and blazed ahead 3-0 on a warm and windy afternoon on Court Philippe Chatrier before world number 43 Muchova settled the nerves, got on the board and threatened to break back.
Muchova had chances in the fifth game of the first set but the 26-year-old struggled to finish them off and found herself in more trouble in the next before bailing herself out with a tight hold thanks to a delightful drop shot and backhand winner.
The Czech, who prevailed the only time the pair faced off in Prague in 2019, launched herself into Swiatek’s second serve but sprayed far too many errors and allowed her opponent to go up a set in 44 minutes with another break.
Swiatek continued to benefit from Muchova’s mistakes from the baseline and at the net to build a commanding 3-0 lead in the second set but the Czech fired a rocket of a forehand to break back and then level at 3-3.
Muchova began to grow in confidence and attacked with more accuracy to heap pressure on Swiatek, who hit a double fault to gift Muchova the chance to even things up in the next game but there was yet another twist in the tale.
After breaking back to make it 5-5, Swiatek surrendered her serve again but saved two set points before Muchova pulled off a magical volley at full stretch to set up another and finally forced a decider.
Muchova was brimming with self-belief, having edged Aryna Sabalenka in a three-setter in the semi-finals, and went ahead in the final set, but Swiatek shrugged off the early break and wrestled back the momentum by winning three straight games.
The Polish top seed dropped serve in the seventh game but broke back instantly and produced a tight hold to inch closer to the title, which she wrapped up when Muchova double faulted to spark emotional scenes on centre court.
Swiatek’s third win in Paris put her level with greats and modern day three-time champions Serena Williams, Monica Seles and Arantxa Sanchez Vicario.
(With Reuters Inputs)