City dominated the first half at Wembley but were unable to turn their control of the final into a half-time lead.
It was a much closer match after the break, but Aymeric Laporte’s 82nd-minute header from Kevin De Bruyne’s free-kick proved decisive.
The victory was City’s seventh major title under Guardiola, while his side are also likely to lift their third Premier League title in four seasons and are in the semi-finals of the Champions League.
And while they were knocked out of the FA Cup at the semi-final stage by Chelsea last weekend, Guardiola was quick to highlight his side’s form since the turn of the year, which has left them still capable of winning three trophies in a single campaign for a second time in the space of three seasons.
“Today we were incredible and I’m happy to win the first title [of the season], to win four in a row in this competition, but especially to win 30 of the last 33 matches,” Guardiola told Sky Sports.
“This is amazing, and in this period where we have lockdowns, suffering, a different way of life. We played with incredible personality from the first minute to try and win the game.
“They had a few minutes and some counter-attacks, but in general we played a really good final.”
Despite their impressive first-half display in which they created several clear chances from open play, it was surprising for City to make the breakthrough thanks to a set-piece.
“We had a lot of corners and we are not the strongest [at set pieces],” Guardiola added. “The free-kick [from De Bruyne] was good and [Laporte] did incredible.
“We don’t have time to work [on set-pieces]. Just the principles from the beginning so we know what to do and we just try to recover. It is tough but it is what it is – the schedule is this way.”