The "Bend it Like Beckham" director said she had signed a deal with 20th Century Fox to direct the film, which will star Travolta as villainous oil magnate J.R. Ewing and Lopez as his wife Sue Ellen.
In a statement, Chadha said her appointment meant that the sort of South Asian-themed British films that made her name had "huge credibility and respect in Hollywood."
Chadha, who gave Jane Austen a Bollywood twist in last year's "Bride and Prejudice," is also involved with adapting another TV hit, 60s sitcom "I Dream of Jeannie." She said that film "is still in the pipeline, but there is still some way to go on the script."
Filming on "Dallas" is due to start in October, with the movie slated for a late 2007 release.