Disney+ is promising an intimate portrait of the Oscar-winning actress and singer, 90, which explores the triumphs and personal challenges behind one of cinema's most enduring careers.
The project will revisit Julie's journey from British vaudeville performer to international screen icon through previously unseen archive material and new interviews.
Julie is to be the focus of the documentary from acclaimed filmmaker RJ Cutler, whose previous work includes Billie Eilish: The World's A Little Blurry and Martha.
Disney+ confirmed the film will debut in 2027, with an official title and release date to be announced later.
Best known for starring in Mary Poppins, The Sound of Music and The Princess Diaries, Andrews remains one of Hollywood's most celebrated performers, with generations of audiences associating her with some of the most influential family films and musicals ever made.
The announcement also follows renewed interest in Andrews' legacy as Disney continues to expand and revisit many of its classic properties, while The Princess Diaries franchise has remained in the spotlight following development of a third film starring Anne Hathaway.
According to Disney+, the documentary "offers an intimate and revealing look at Andrews' extraordinary journey, from her early days in British vaudeville to her meteoric rise as a global superstar".
It added about the project: "Marked by resilience, heartbreak, reinvention and enduring grace, her story goes far beyond the spotlight."
The streamer said the film will feature "rare, never-before-seen archival footage and candid new interviews", offering audiences unprecedented access to Andrews' life and career.
Andrews won the Academy Award for Best Actress for Mary Poppins in 1965 before cementing her place in film history with performances in The Sound of Music, Victor/Victoria, The Americanization of Emily and Disney's The Princess Diaries films.
Her career also spans acclaimed stage performances, bestselling books and television work, while her distinctive voice became recognised around the world long before she suffered the vocal injury that dramatically altered her singing career.
The documentary is also being produced by RJ Cutler alongside Trevor Smith, Elise Pearlstein, Jane Cha Cutler and Jonathan Ruane, with Mark Blatty serving as executive producer. It is produced by Sony Pictures Television's This Machine.
Speaking about the project, RJ Cutler said: "Julie Andrews is not simply a beloved performer.
"She is a cultural touchstone, a figure woven into the fabric of how generations of people understand joy, resilience and grace.
"Most people don't know the extraordinary challenges she's had to overcome throughout her life, all of which we delve into in this film.
"To sit with Julie, to be allowed into her inner world, to watch her reflect on a life that has shaped so many other lives was an experience I will forever cherish. She gave us her full self, without armour, without pretence. And what we found was someone even more extraordinary than the icon.
"I am humbled by her talent, in awe of her strength and honoured by her trust."