The first, Fantastic Beasts and Where to Find Them, will be directed by David Yates, who directed the last four Harry Potter movies, and reunite the same filmmaking team.
It is described as "set in an extension of her familiar wizarding world, featuring magical creatures and characters inspired by Harry Potter's Hogwarts textbook and its fictitious author".
A second movie is set for release in 2018 and a third in 2020, . The first movie was announced last month.
Rowling, who has sold more than 450 million copies of the Harry Potter books, announced in September that Warner Bros had approached her about doing Fantastic Beasts.
"I thought it was a fun idea, but the idea of seeing Newt Scaramander, the supposed author of Fantastic Beasts, realised by another writer was difficult.
"Having lived for so long in my fictional universe, I feel very protective of it," she said, explaining her decision to write the screenplay.
Rowling's Harry Potter books - which were published from 1997 to 2007 and tell the story of the young wizard and his friends at the Hogwarts school of magic - spawned a string of hit films and the Pottermore website.
The movies made global celebrities of its actors, principally Daniel Radcliffe as Harry, Emma Watson as Hermione Granger and Rupert Grint as Ron Weasley.
Earlier this month Rowling tweeted some cryptic clues about the films, which sent online users into a frenzy.
Fans noticed that the tweet might be an anagram for "Harry Returns! Won't say any details now! A week off! No comment."
She later tweeted another post with the hashtag #helpfulhint: "The solution is the first sentence of a synopsis of Newt's story. It isn't part of the script, but sets the scene."
