The film will be directed by 'The Giver' director Phillip Noyce from an adaptation of Philip Roth's Pulitzer Prize-winning novel.
Connelly will play Dawn, the wife of Seymour "Swede" Levov, McGregor's character.
It is the third Roth adaptation by Lakeshore Entertainment after 'The Human Stain' and 'Elegy'. Lakeshore's Tom Rosenberg and Gary Lucchesi are producing the film, said the Hollywood Reporter.
"Jennifer Connelly is one of the great actresses of our time. We always wanted her to play Dawn in American Pastoral and we're thrilled to be working with her," Rosenberg said.
The film's shooting is set to star in March 2015.
