The pair will feature in Roger Donaldson's new movie alongside Clive Owen and Anil Kapoor, reports Deadline.
The financial drama is a cautionary tale set in three cities in the months leading up to the Dow Jones all-time stock market high.
Melancholia's Dunst and Bloom play a couple struggling to buy their first home together in London.
Owen will take on the role of a greedy hedge fund manager in New York, while Kapoor is a crooked cop in Mumbai.
The film reunites Dunst and Bloom, who starred in Cameron Crowe's Elizabethtown.
Cities is expected to debut next year.
Watch Kirsten Dunst talk to Digital Spy about Melancholia below: