He made the announcement Sunday at the site of the Sheetrock 400 in Joliet, Ill. He will drive the No.42 Dodge currently being piloted by Casey Mears for Target Chip Ganassi Racing.
"I have seen this guy adapt to a car like no driver like I have ever seen," said Ganassi about Montoya. "No question, he can adapt to a 'Cup' car. He will be doing Cup and Busch. I know my team is up for it."
Montoya, a native of Colombia, won the 2000 Indianapolis 500 while driving for Ganassi. Currently, he is sixth in the F1 standings, 62 points behind the leader, Renault's Fernando Alonso.
In six years of F1 racing, Montoya has earned seven wins and 12 poles. He won the 1999 CART championship, compiling seven wins and seven poles.
Previously, Mears announced that was leaving Ganassi to drive for Hendrick Motorsports.