Castroneves began karting at age ten in Ribeirão Preto, Brazil, inspired by Ayrton Senna. He progressed through Formula Chevrolet Brazil, Formula 3 Sudamericana, the British Formula Three Championship, and Indy Lights before entering CART with Bettenhausen Racing in 1998. He joined Team Penske in 2000 following Greg Moore's death, winning three races that season. Castroneves remained at Penske for the bulk of his open-wheel career, finishing runner-up in the IndyCar Series in 2002, 2008, 2013, and 2014. He was a perennial championship contender but never won the IndyCar title.
Beyond his Indianapolis 500 victories, Castroneves won the Dancing with the Stars fifth season in 2007 with professional dancer Julianne Hough, raising his public profile well beyond motorsport. He was acquitted in a 2009 tax evasion trial after the jury found him not guilty on all six criminal counts.
Castroneves made his endurance racing debut in 2006 and contested the 24 Hours of Daytona with Michael Shank Racing in 2007. From 2008 he drove Penske's Porsche RS Spyder LMP2 entries, winning the Petit Le Mans LMP2 class that year with Ryan Briscoe.
In 2016 Roger Penske offered Castroneves a full-time sports car career. He transitioned to Penske's IMSA programme ahead of the 2018 season, testing in the 2017 Petit Le Mans to prepare. Partnering Ricky Taylor in the number 7 Acura ARX-05 for the full 2018 and 2019 IMSA seasons, with Graham Rahal added for endurance rounds, the pair finished seventh in the Prototype standings in 2018. In 2019 they improved to third in the DPi standings with three podium finishes.
The breakthrough came in 2020. Castroneves and Taylor won consecutive races at Road America, Road Atlanta, and Mid-Ohio over the course of the season. They won the DPi Drivers' Championship at the season-ending 12 Hours of Sebring, Castroneves' first outright championship in auto racing, by one point over Ryan Briscoe and Renger van der Zande.
Castroneves won the 2021 24 Hours of Daytona as an endurance driver for Wayne Taylor Racing, sharing with Filipe Albuquerque, Alexander Rossi, and Renger van der Zande. He then joined Meyer Shank Racing (MSR) for the 2022 and 2023 IMSA Endurance Cup races. He won the 24 Hours of Daytona in 2022 with MSR, fending off Ricky Taylor in the final laps, and claimed a third consecutive Daytona win in 2023 sharing with Tom Blomqvist, Colin Braun, and Simon Pagenaud. He also won the 2022 and 2023 Petit Le Mans with MSR teammates. MSR departed IMSA following the 2023 season.
Castroneves won the Indianapolis 500 at his first attempt in 2001 leading the final 52 laps. He repeated in 2002 in controversial circumstances when race officials rejected a last-lap challenge from Paul Tracy. His third victory came in 2009, and his record-tying fourth in 2021 with Meyer Shank Racing, passing Alex Palou in the closing stages. He is one of four drivers to win the event four times.
Castroneves was inducted into the Motorsports Hall of Fame of America in 2022 and the Indianapolis Motor Speedway Hall of Fame in 2025. He received the 2001 Indianapolis 500 Rookie of the Year award and the 2004 Scott Brayton Award. He has a daughter with his long-term partner Adriana Henao.