In 2009, Barrett expressed an interest in running IndyCar Series races after the series merged with Champ Car. At the Nationwide Series race at Kansas Speedway, he officially announced that he had joined Team 3G full-time to drive the No. 98, while also running 19–21 races in the Nationwide Series. In his IndyCar debut at the Honda Grand Prix of St. Petersburg, Barrett qualified 21st and finished 12th, four laps behind race winner Ryan Briscoe. Barrett struggled during the season, including failing to qualify for the Indianapolis 500 and missing the ABC Supply Company A.J. Foyt 225 due to a crash in practice, and was eventually replaced by Jaques Lazier. Barrett returned to the series later in the year at Twin Ring Motegi, where he finished 19th.