Kimball began his motorsport career in karting in 1997, which he held until 2001. In 2002 he made in the U.S. Formula Dodge his first experience in Formula racing and in 2003 took on the U.S. F2000 National Championship, the third overall occupied, in part. After he became third in the British Formula Ford Winter Series in the winter, Kimball went in 2004 in the British Formula Ford at the start and finished with two wins fourth place in the overall standings. He also took part in two races of the New Zealand Formula Ford, where it was 18
2005 Kimball moved to the British Formula 3 Championship at Carlin Motorsport. With five wins and a total of 13 podium finishes saw him win Álvaro Parente the runner-up title in this series. In 2006, Kimball Signature-Plus in the Formula 3 Euro Series. He succeeded in the new series not to build on the successes of the previous season, and he finished with a victory as the best result in eleventh place overall. He was better than the later masters of the Euro Series Romain Grosjean, who was one of Kimball's teammate for the 2006 season.
2007 Kimball went for Victory Engineering in the Formula Renault 3.5 at the start. After seven race weekends he had to finish the season for health reasons, as had been found in type 1 diabetes him. At the end of the season, he finished 24th overall. 2008 Kimball returned to the Formula 3 Euro Series. Starting for the Prema Powerteam he succeeded with a second place in the first race a good start to the new season. Nevertheless, he was after three race weekends replaced by Stefano Coletti, because he could not pay his race seat. At the end of the year he took part in a race weekend of the A1GP season 2008/ 2009 for the U.S. team.
2009 Kimball returned back to the United States and started for the team PBIR in the Indy Lights. With a fourth place as best result he finished at the end of the season tenth overall. 2010 Kimball joined the team AFS Racing / Andretti Autosport, which won in the preseason with JR Hildebrand the drivers' title. With four second-place finishes for the best results he was the best American pilot at the end of the season in fourth place in the overall standings.
2011 Kimball moved to Chip Ganassi Racing and completed his first season in the IndyCar Series. He went to a satellite team 's achievements. While his teammates achieved podium finishes and Dario Franchitti in addition won the championship, Kimball finished the season off with a ninth place as the best result on the 19th place overall. 2012 Kimball went again for Chip Ganassi Racing in the IndyCar Series at the start. His first IndyCar podium placement Kimball scored the Honda Indy Toronto with a second place. When Honda Indy 200 at Mid-Ohio Kimball paused due to injury, after he had a week earlier suffered a hand injury during test drives on the track. The season he finished as the worst Ganassi pilot on the 19th Place. 2013 remained at Kimball Ganassi in IndyCar Series. In the second race in Birmingham Kimball led the race between time and finished it in fourth place. After three more top- 10 finishes in the next eight races Kimball was second in Long Pond behind his teammate Scott Dixon. Three races later, he scored his first IndyCar victory at the Honda Indy 200 at Mid-Ohio. He thus became the first diabetic who has won an IndyCar race. He improved in the standings to ninth place overall, while Dixon won the championship. In addition, Kimball took part for his team at the 24 - hour race at Daytona in the Rolex Sports Car Series. He started in a Riley - BMW won the race and along with his team-mate Juan Pablo Montoya, Scott Pruett and Memo Rojas.
2014 Kimball denies his fourth IndyCar season for Chip Ganassi Racing.
Through his diabetes disease Kimball needs a special treatment. In its body, a blood sugar sensor is implanted, which transmits the corresponding information to both a display in the vehicle as well as to the team. To stabilize the blood sugar Kimball gets an insulin injection at the pit stops. The insulin supplier, Novo Nordisk, beyond is Kimball's personal sponsor and was both at the Indy Lights as well as the main sponsor of the IndyCar Series cars.
- 2005: British Formula 3 (2nd place)
- 2006: Formula 3 Euro Series (No. 11)
- 2007: Formula Renault 3.5 (ranked 24)
- 2008: Formula 3 Euro Series (No. 17)
- 2009: A1GP
- 2009: Indy Lights ( place 10 )
- 2010: Indy Lights (4th place )
- 2011: IndyCar Series ( No. 19 )
- 2012: IndyCar Series ( No. 19 )
- 2013: IndyCar Series (No. 9)
- 2013: Rolex Sports Car Series, DP ( place 31 )
- 2014: IndyCar Series