The adaptation was written by, and will be directed by, Lisa Azuelos, who created the French film, Frank PR said in a news release.
"I am thrilled that Marlo is joining the cast of 'LOL' to play my mother," Moore said in a statement. "I have loved her since 'That Girl' and have been inspired by her work in front and behind the scenes ever since."
Principal photography on "LOL" is to begin this summer in Detroit. Michael Shamberg and Stacey Sher of Double Feature Films and Tish Cyrus will produce the film.
Thomas has just finished her sixth book, "Growing Up Laughing," a memoir of her life as the daughter of comic Danny Thomas and as a comedienne in her own right. The book is to be published by Hyperion Sept. 28.