Pagenaud, driving the #22 Hewlett Packard Enterprise Chevrolet for Team Penske, won the 85-lap race at Sonoma Raceway by 3.2523secs over Graham Rahal, a dominating performance that saw the Frenchman lead all but nine laps and clinch the series crown by 127 points over team-mate Will Power.
"I tried to take my future in my destiny by being aggressive and going as fast as I could," Pagenaud said, "Clearly, we had a phenomenal car, I think a very dominant car today, so we could do that. I just enjoyed driving today. It was an incredible day and I think it just shows the strength of the 22 team for the whole season."
Pagenaud started the race from the pole position and surrendered the lead only during pit-stop cycles in winning for the fifth time this season and ninth of his Indycar career. Power, in the #12 Verizon Team Penske Chevrolet, was running second to Pagenaud until a clutch malfunction stopped his car on track on lap 36. The Autralian fell eight laps off the pace while repairs were made and finished the race in 20th place, but retained second in the championship for the fourth time in his twelve-year Indycar career.
"It was obviously disappointing to have that gearbox problem," Power said, "but I think Simon was going to be tough to beat as far as the championship goes. Maybe we could have beaten him for the [race] win, but I doubt it if everything just played out as it was. But it was still a very strong year, with four race wins. I won a 500-mile race [at Pocono] - not the right one, but still a 500-miler."
The championship was the 14th in Indy cars for Team Penske, celebrating its 50th anniversary in racing this year, and the race win was the team's 187th in Indycar competition - more than any other team. Pagenaud, who set a track record in qualifying on the 2.385-mile permanent road course Saturday, etched his name into the Sonoma books again on raceday with his average race speed of 101.181mph.
The Frenchman – who began his Indycar adventure as team-mate to Power in the Team Australia CART initiative - now enjoys the spoils of the championship, including a $1m prize and official presentation of the Astor Cup that will take place on 4 October at the IndyCar Championship Celebration in Indianapolis. It gives the 32-year old Frenchman two weeks to let the magnitude of his accomplishment sink in.
"It's unbelievable," he admitted, "I think I will realise it more tomorrow. There is so much emotion right now, to be honest, I can't find the words. My whole career has been about this, about today and getting to this point and to this level."
Team Penske completed a 1-2-3 sweep of the championship when Helio Castroneves finished seventh in the race to edge Ed Carpenter Racing's Josef Newgarden by two points in the standings. It marked the first time the same team took the top three championship positions since Penske also accomplished the feat in 1994 with Al Unser Jr, Emerson Fittipaldi and Paul Tracy.
With his second-place race finish in the #15 Steak 'n Shake Honda, Rahal advanced to fifth in the championship, the highest-placing Honda driver.
"Good day, good way to end it," said the Rahal Letterman Lanigan Racing driver. "I wanted to get Pagenaud, but when I'd get behind him, I'd get massively loose. I thought at one point it was best I salvage a second place rather than do something stupid."
As he did in winning the 100th running of the Indianapolis 500 presented by PennGrade Motor Oil in May, Alexander Rossi ran out of fuel and coasted to the finish line in Sonoma. He was passed by Andretti Autosport team-mate Ryan Hunter-Reay for fourth place, but still secured Sunoco Rookie of the Year honours for the season, just as he did for the Indy 500.
Chevrolet, which won 14 of the 16 races this season, also clinched its fifth consecutive manufacturers' championship by 104 points over Honda. Chevy has taken the honour every year since manufacturer competition resumed in the Verizon IndyCar Series in 2012.