Racing his final Grand Tour for Ineos Grenadiers, Carapaz burst clear of the breakaway to clinch his third stage win ahead of Thymen Arensman (Team DSM) and Juan Ayuso (UAE Team Emirates).
Carapaz left Sergio Higuita (Bora-Hansgrohe) at the peak of the final climb with seven kilometres remaining and, with the day's final KOM points in hand, hit the plateau with a 20-second buffer Arensman could only limit to eight.
Ayuso was next to cross the line, 13 seconds behind Carapaz, with Jai Hindley (Bora-Hansgrohe) and Enric Mas (Movistar) joining him two seconds ahead of overall winner Evenepoel (Quick-Step Alpha Vinyl).
With Primož Roglič (Jumbo-Visma) forced to abandon La Vuelta after Stage 16, Mas loomed as Evenepoel's only GC threat in the 181-kilometre trek to Puerto de Navacerrada.
Mas trailed the Belgian by 2'07" at the start of the day but could only take two seconds back once they'd navigated the three Category 1 climbs and two Category 2 ascents on offer.
Evenepoel's 2'05" lead has all but secured his first Grand Tour title - and Belgium's first since Johan De Muynck in 1978 - providing he makes it through the final sprint stage in Madrid.
The 22-year-old admitted stress had been a factor in the lead up to the stage but quickly rediscovered his composure once the racing began.
"I didn’t sleep too much last night, and this morning, before the start, I was quite stressed," Evenepoel said. "But during the race I felt better and was relaxed, having confidence in myself and the Wolfpack.
"I knew that all I had to do was control and follow my opponents, and everything ran smoothly, just as we wanted.
"This is the biggest victory, the biggest moment of my career, and it feels incredible.
"It’s for my parents, my fiancé, my teammates. It’s the result of many weeks and months of hard work and sacrifices and always believing in yourself.
"I love racing in Spain, I have had success here since my first pro season and to win La Vuelta is a dream.
"It wasn’t easy, I had some stiff opposition, but I did it and I can’t tell you how much this means for me."
La Vuelta concludes tomorrow morning LIVE on SBS and SBS On Demand from 1:20am (AEST).
