The "Fleabag" creator and star will take on a mystery role opposite movie veteran Ford, who is set to return as the iconic archaeologist for the fifth film in the blockbuster franchise.
"Logan" director James Mangold will take over the reins of the film series from Steven Spielberg, who will instead serve as a producer, alongside longtime collaborator Frank Marshall, and Lucasfilm President Kathleen Kennedy.
The news of Waller-Bridge's casting comes as studio bosses also confirm John Williams' return as the film's composer.
In a statement, Mangold said, "I'm thrilled to be starting a new adventure, collaborating with a dream team of all-time great filmmakers."
"Steven, Harrison, Kathy, Frank, and John are all artistic heroes of mine. When you add Phoebe, a dazzling actor, brilliant creative voice and the chemistry she will undoubtedly bring to our set, I can't help but feel as lucky as Indiana Jones himself."
"Indiana Jones 5" has been in the works since its official announcement in 2016 and, after a series of delays last year (20), Disney chiefs finally set the movie's release date for July 2022.
The film will be the follow-up to 2008's "Indiana Jones and the Kingdom of the Crystal Skull", which earned over $790.6 million (£568.7 million) at the global box office.