The yet-to-be-titled movie, starring Reese Witherspoon, will be directed by Todd Haynes, who previously made a biopic about musician Karen Carpenter.
Ephron's screenplay has been reworked by Pulitzer Prize-winning playwright Doug Wright, reported BBC online.
The writer had also been set to direct the film before she died aged 71.
Witherspoon has had a long-standing interest in portraying Lee, who died in 2002.
The singer was best known for her hits including 'Fever' and 'Is That All There Is?'