The 26-year-old Movistar rider, who won stages four and 14, took the maglia rosa on his second stage win and kept it on his shoulders until the final day’s individual time-trial.
Carapaz, who also won this year’s Vuelta a Asturias, claimed an overall time of 90:01:47. Vincenzo Nibali (Bahrain-Merida) placed second on the general classification and Primoz Roglic (Team Jumbo-Visma) third.
“This is the biggest moment of my sporting life. In this final time-trial I just suffered from start to finish until I reached the arena of Verona. It’s fabulous to win the Giro d’Italia,” said Carapaz.
“In my four years in European cycling, I realised that opportunities have to be caught. The thirty seconds I gained on stage 15 were fundamental. I profited from [Vincenzo] Nibali and [Primoz] Roglic watching each other. That’s where the Giro was decided. For me, it’s only the beginning I think. We always dream for more.”
The 17km time-trial was won by Chad Haga (Team Sunweb) in 22:07, with Victor Campenaerts (Lotto Soudal) and Thomas De Gendt (Lotto Soudal) second and third respectively.
“This is my first World Tour win but I started this morning believing strongly that I could win,” said Haga.
“I saved my legs these past few days. Watching Roglic and Nibali on TV, I had to convince myself that they were tired. It’s a huge emotion. I’m speechless.”
Haga held the lead after starting 38th and kept it until the last rider went down the starting ramp, which was Carapaz, who placed 36th.
Roglic, who won the first and second time-trial, had the clock against him and managed to finish in 22:33, ninth fastest.
Pascal Ackermann (Bora-Hansgrohe) won the sprinter leader’s jersey, while Giulio Ciccone (Trek-Segafredo) claimed the King of the Mountains jersey and Miguel Angel Lopez (Astana Pro Team) the best young rider jersey.
“The atmosphere in the arena is fabulous. I have never experienced anything like this before. It makes me feel special about the getting the Cyclamen jersey, which was a childhood dream,” said Ackermann.
“Coming to the Giro, I was only hoping for a victory but after I won two stages, it looked worth trying to go for the jersey as well. But I was very disappointed after my crash. I lost a lot of points but we kept working on getting it back.
“I wasn’t expecting what I’ve experienced over these three weeks and I’m just happy about everything.”