Overall, the 22-year-old beat Nairo Quintana by 39 seconds, allowing the Movistar rider to grab just a few from him in the 110km loop around Nice.
Bernal's Sky team-mate, Michal Kwiatkowski, finished third, one minute and three seconds off the pace.
"It's a really good feeling. I can't believe I just won Paris-Nice," Bernal said. "It's incredible for me. I'm happy.
"Was it hard to stay calm? Yes and no. When some riders started to attack, I couldn't follow them but I also knew I had a good team, a strong team and it can control the escapees.
"It was not difficult to be calm because I really believed in my team. The whole team was riding very hard in the front. We knew it was the last day and they pulled very hard.
"Quintana was very strong but I had Kwiatkowski Sosa, Tao… When Quintana attacked, I thought maybe if I follow him, I can stay with him. But then I'm alone and I preferred to wait a little bit and stay calm.
"Nicolas Portal, our team director, knows everything about this race, all the details, the winds, the roads, the gaps. In the finale, I knew that with a 45 seconds lead, it was enough to win."
Australia's Jack Haig (Mitchelton-Scott) finished fourth for a career-best result in a race featuring some of the best in the world.
“It is pretty amazing to finish fourth to be honest," Haig said. "And through a couple of different circumstances the team plan changed and I was very lucky to have all the team behind me for the majority of the week. To go top five in a pretty prestigious race is pretty special.
“Today Team Sky did their general tactic of riding a really solid pace basically from the start today and people are attacking and they just set their tempo. I just sat tight and sat behind them and paced myself and at one point I felt a bit pinned but I just held my breath and waited behind Sky and that was enough to move up and finish in fourth place so I am super happy.”
Izagirre beat Oliver Naesen (AG2R) and Wilco Kelderman (Sunweb) in the punchy 110km stage held in and around Nice.
"It was hard to finally raise the arms but what a nice day in Nice today. It was a very spectacular stage," Izagirre said.
"This time I couldn't be in contention for the GC but I managed to win a stage. With Luis Leon Sanchez, we decided to go in the breakaway and then we saw some guys coming back from behind like Quintana, and then Miguel Angel Lopez told us he was tired.
"So in the last climb, I decided to go and give it my all. And it worked. It's amazing the number of stages we have been winning with Astana. Lutsenko won in Tirreno yesterday and me today. It's exceptional."
Sky have now claimed six of the last eight editions of the 'Race to the Sun' to reaffirm their stage race dominance.
Into the first climb of the day, on the heels of Bob Jungels (Deceuninck-QuickStep), a group of 37 riders emerged, including Izagirre, Naesen, Kelderman and Thomas De Gendt (Lotto-Soudal), who picked up enough mountains points on the stage to secure the classification.
In the descent Matteo Trentin (Mitchelton-Scotts) broke clear and reached the top of Cote de Chateauneuf with a 10 second lead over his former breakaway companions.
Tejay Van Garderen (Education First) and Julien El Fares (Delko-Marseille-Provence) then joined him over the top of the Col de Calaison with a 30-second lead over the original break.
On the Cote de Peille, as Van Garderen went on his own, Quintana (Movistar) surged at the front of the peloton and joined forces with team-mates Marc Soler and Hector Carrretero to try and upset Team Sky and Bernal.
At the top of the climb, the hyperactive Quintana was leading a group of 12, including Soler, Van Garderen, Izagirre, Naesen, Kelderman and Mitchelton-Scott's Simon Yates.
With a 50 seconds lead over the Bernal bunch, Quintana found himself the virtual leader of the race and he moved even closer by winning the intermediate sprint of La Turbie.
On the Col d'Eze Quintana took the race into his hands, reaching the top in the front with a 55 seconds lead over the yellow jersey group.
During the descent he joined forces with Education First Daniel Martinez and Van Garderen and the gap remained around 55 seconds. Dropping into Nice, Quintana recieved no help from his group and Izagirre responded with a decisive attack.
Ion Izagirre wins the final stage of the 2019 Paris-Nice. (Getty) Source: Getty
