Harvick became the fifth IROC rookie to win the championship but the first in 15 years. He joined Mark Donohue in 1974, Harry Gant in 1985, Al Unser Jr. in 1986 and Geoff Bodine in 1987.
Harvick earned his spot here by winning the 2001 Busch Grand National series title. He collected $250,000 for his second circuit championship in as many seasons.
"When we came into the year it was something that just really neat to be in the IROC series, and race against all the different divisions and people that are driving the IROC cars," Harvick said. "It is just an honor to drive them, but to come to the last race in the year and have a shot to win the championship was really neat for me."
Jarrett scored a flag-to-flag victory in a 40-lap race that had little drama. He started and was tested only at the beginning when Ken Schrader -- substituting for injured World of Outlaws sprint car driver Danny Lasoski -- tried an unsuccessful pass. From that point, Jarrett drove away from the field.
It was the second straight race that the winner has led the entire way. Buddy Lazier also scored a flag-to-flag victory at Chicagoland Speedway last month.
"It was a great race car," said Jarrett, who notched his second career IROC win. "We raced very hard in it. It's pretty nice. I knew it was important to get my car out front and I fought Ken Schrader as hard as I could there on that first lap, trying to get the lead.
"I knew the car was going to tighten up later on and if I could get out front, I'd have a better chance."
Two-time Indianapolis 500 Helio Castroneves finished second, 0.380 seconds behind Jarrett.
"My car started to push, so I moved up to save the tires a little bit," Jarrett said. "Whenever he got a little bit closer, I went back down to my groove and was able to pull away a little bit."
Castroneves admitted he is unfamiliar with driving stock cars but performed well in Saturday's race on a track where he has achieved his greatest success.
"I think I'm learning a lot," Castroneves said. "I've been learning with all those drivers, especially with the guys that are teaching us during the practice. Also the NASCAR guys, you know, they give little tips. They think they don't give you any tips, but even the little ones, you can still improve.
"Today, Dale Jarrett didn't make any mistakes and, obviously, he knew what he was doing. I had a good time."
Schrader put Lasoski's car in third, followed by 1996 Indianapolis 500 winner and 2000 IRL champion Buddy Lazier. Harvick was next, despite driving on an empty stomach.
"I was nervous this morning, and didn't eat," Harvick said. "I was pretty whipped out when I got in there. I forgot to eat lunch today, so I paid the price for that one, but it was a great experience, and hopefully next year we can do it again."
Al Unser Jr., who did not compete because he is in an alcohol rehabilitation center, finished seventh with 39 points. He was followed by Jack Sprague and Scott Shard with 36, Sterling Marlin and Sam Hornish Jr. with 35 and Lasoski with 30.