The network said Friday that the project, titled "Everything is Copy," will also have Vanity Fair editor Graydon Carter as executive producer.
Ephron died at age 71 last year. She was the writer behind films "When Harry Met Sally," "You've Got Mail" and "Sleepless in Seattle." Her last project is the current Broadway play about journalist Mike McAlary, with Tom Hanks in the starring role.
The documentary's title is a reference to Ephron's feeling that all of life's experiences provide fodder for a writer.
The documentary project was first reported in the Hollywood Reporter.