Coming back from 1-3 down in the decider and saving three match points in total, Swiatek claimed a 7-5, 4-6, 7-6 (9/7) victory to secure the Madrid Open trophy for the first time.
"Well, who is going to say now that women's tennis is boring, right?" said Swiatek.
Swiatek, who picked up the 20th title of her career, and ninth at the WTA 1000 level, has now won her last eight consecutive finals and joins Elena Rybakina with a tour-leading 30 victories this season.
The 22-year-old Pole confessed she felt tight in the first two hours of the contest but drew inspiration from Rafael Nadal, and his ability to step up mentally when it mattered the most.
"I was surprised that in the third set I felt the best mentally," said Swiatek, who improved to 7-3 lifetime against two-time Madrid champion Sabalenka.
"One thing that came through my mind was that I think Rafa had a couple of matches like that.
"I remember exactly when he was playing (Daniil) Medvedev in Australia (Open final in 2022) and it clicked for him. He also struggled for a bit of time, he was tense and I think stressed. That kind of gave me hope that maybe it will click, even after two hours."
In warmer temperatures but breezier than usual conditions at the Caja Magica, the pair traded breaks to kick off the final and were neck and neck until Swiatek drew a forehand error from Sabalenka to break for 6-5 and closed out the 61-minute opening set on her first opportunity.
Despite squandering a 2-0 lead early in the second, Sabalenka manifested a set point on Swiatek's serve in game 10, forcing a decider with a lightning-fast down-the-line forehand winner.
It was the fifth time in six matches this fortnight that Sabalenka found herself embroiled in a three-set duel and she was clearly ready to go the distance.
'Intense' final
The defending champion broke for 3-1 in the decider, peppering Swiatek with deep, powerful shots, but her lead was short-lived.
Swiatek saved a pair of match points on her own serve at 5-6 as the high-quality affair fittingly went to a deciding tiebreak.
Sabalenka produced an ace to save match point at 5-6 in the breaker and saw one of her own slip away as Swiatek survived for 7-7.
Moments later, the Polish world number one flung herself to the ground in disbelief as she sealed a heroic victory on a long backhand from Sabalenka.
"I think it was the most intense and, like, crazy final I played," said Swiatek after the match.
Despite the loss, Sabalenka feels she has recaptured her best form that saw her successfully defend her Australian Open title in January.
The world number two admits her level dipped after Melbourne but her long battles in Madrid have helped her get back to her battling best.
She said the tight defeat is a "tough one to accept" but she's proud of her efforts against her fellow "Big Three" rivals, Rybakina and Swiatek this fortnight.
"I really want to see many more finals against her," said Sabalenka.
"I really hope that we'll be able to increase the level every year. I'm really happy to be one of these Big Three, as you call us.
"It's really motivating me a lot to keep working and to keep improving myself just so I stay there and get as many wins against them as I can."
