Tagliani will drive the No. 30 Chevrolet for Turner Motorsports. The Canadian driver is a fan favorite at the Circuit Gilles Villeneuve, and finished second in last year's race.
He says he loves racing in Montreal, and it gives him a chance to spotlight his sponsors all over his home country. The IndyCar schedule takes Tagliani to Toronto and Edmonton.
The announcement Wednesday comes on the heels of Tagliani's season-best finish in IndyCar. He passed Dario Franchitti for the lead on the first lap, led 49 laps and finished fifth.
The deal for the Montreal race on Aug. 18 came together after IndyCar canceled its event in China.