Bagnaia and Pramac title rival Jorge Martin came into the championship decider in Valencia split by 14 points after the latter won the sprint on Saturday.
But the championship battle came to a halt on lap six of the grand prix when Martin collided with Honda's Marc Marquez on the eight-time world champion's final appearance for the team while battling for fifth.
Bagnaia went on to win the race for his second title in a row, becoming the first rider since Marquez to win consecutive titles.
Asked how he felt about that fact, Bagnaia said: "I feel well, it's fantastic. And even more with the number one, finishing second in the championship could be a very bad result.
"I couldn't be happy with a second position in the championship because a number one plate means that you need to demonstrate that you are the number one and I think we did everything perfect to be considered the number ones.
"Even more in the second part of the championship, because we were the faster many times but we managed always to be competitive and faster and stronger on Sunday, that is the main race, the race that gives to you more points.
"So I think last season was a season to be very proud, but this season even more because the number one plate with many mistakes, bad luck in some situations and we won the title the same. So we have to be very proud."
Comparing his second title to his first, for which he defeated factory Yamaha rider Fabio Quartararo, Bagnaia said he was "more under pressure" in 2022 and said Quartararo's bike was "not giving to him the possibility to fight against me."
He also said fighting a fellow Ducati rider was tough given the pair are able to share data.
Asked how he was a better champion compared to last year, Bagnaia said: "The consciousness of being more competitive.
"Last year I arrived here and I was very more under pressure, with just a race and 23 points of advantage.
"So it was a totally different situation, this time I was starting today with 14 points, Jorge yesterday was super fast and I think I did a big step in front in terms of being calm in terms of managing better situations.
"My team have helped me a lot too and I think I will continue trying to understand, trying to learn from my mistakes.
"Last year I thought I was ready, I was learning, but this year I started and second or third races I did the same mistake as last year.
"So I think every year is a process to improve myself, so we have to continue and keep going like this learning and improving every time."
