The 31-year-old Ericsson from Kumla, Sweden, led three times for 13 of 200 laps before fending off Pato O'Ward in a two-lap shootout to claim his first Indy 500 title.
The third-generation Andretti driver from Nazareth, Pennsylvania, is primed to reach a milestone start in his 17th consecutive appearance in the Indianapolis 500.
“I miss this thing so much," Castroneves said. "I know I didn’t finish in the top 10. One spot behind, but let me tell you, what a great group of guys. They did a phenomenal job today."