The most experienced driver in Formula One history, Barrichello switched to his native stock car category full time in 2013 after a single season in IndyCar.
After an indifferent start to life in tin-tops, Barrichello scored a maiden podium mid-way through last season.
Last weekend he took his Full Time Sports-run Chevrolet to victory at Autódromo Internacional Ayrton Senna in Goiania, which hosted round eight of the campaign. Thiago Camila was second, just a tenth shy of Barrichello, with Galid Osman third.
Former F1 racers Antonio Pizzonia, Ricardo Zonta, and Luciano Burti also contested the Goiania event.
Barrichello scooped a $440,000 prize for winning the race, half of which he will donate to his Full Time Sports team, with the other half going to the Barrichello Kanaan Institute he runs with IndyCar veteran Tony Kanaan.
Atila Abreu finished the race in P4 and continues to lead the championship standings, while Barrichello has now climbed to fourth, just seven points shy of top spot.