The Oscar-winning director is attached to make the big-screen adaptation of the much-loved book for DreamWorks, said The Hollywood Reporter.
Spielberg, who has not directed a film since 2012's Lincoln, is said to be officially committed and is already planning to start shooting in 2015, for a 2016 release.
Various directors, including Chris Columbus and John Madden, had been attached to the film over the years.
The live-action film will be based on the tale of a Big Friendly Giant who becomes friends with a young orphan girl. DreamWorks bought the rights to the book in 2011.
Melissa Mathison, who wrote the script for ET, is writing the screenplay.
The BFG was previously adapted as an ITV animated movie in 1989, starring David Jason as the voice of the friendly giant.