The 25-year-old model and actress will star with Bloom in the "fantasy noir" drama Carnival Row, according to Variety.
Delevingne will play Vignette Stonemoss, a "faerish refugee" who flees her homeland for the "neo-Victorian" city Burgue. The character must contend with "rampant human prejudice" and her own secrets.
The Hollywood Reporter reported The 4400 creator Rene Echevarria will write the script, with Paul McGuigan (Sherlock) as director. Echevarria and McGuigan will executive produce with Travis Beacham (Pacific Rim).
Carnival Row will begin filming in the fall for a 2019 release. Beacham confirmed Bloom's involvement with the project in a tweet last week.
"Massive #CarnivalRow news, you guys: Orlando Bloom is Inspector Rycroft Philostrate. #AmazonOriginal #Legendary," he wrote.
Carnival Row marks both Delevingne and Bloom's major television debut. The actress is known for playing Enchantress in the movie Suicide Squad, while Bloom portrayed Legolas in the Lord of the Rings and The Hobbit films.