Riordan's novel is the first entry in a spinoff series called The Heroes of Olympus, which ties in with his bestselling Percy Jackson & The New Olympians books.
X-O Manowar scribe Robert Venditti will handle writing duties on the project. Hyperion Books, the firm behind the original novels, is on board as publisher.
Powell said: "I'm excited and honoured to be working together with Rob on this project."
Riordan's first Percy Jackson novel The Lightning Thief was adapted for cinema in 2010 with Logan Lerman in the lead role. Its sequel, The Sea of Monsters, will receive the same treatment next year.
The Lost Hero graphic novel will be released in autumn 2014.
Watch a trailer for Percy Jackson & The Olympians: The Lightning Thief below: