* Percy Jackson & the Olympians series (5 books)
* Heroes of Olympus series (5 books)
* Trials of Apollo series (5 books)
* Magnus Chase and the Gods of Asgard series (3 books)
* The Kane Chronicles series (3 books)
* The Demigod Diaries series (4 books)
* The Sword of Summer (first book of the Magnus Chase series)
* The Red Pyramid (first book of The Kane Chronicles series)
* The Son of Neptune (second book of Heroes of Olympus series)
* The Lost Hero (first book of Heroes of Olympus series)
* The Mark of Athena (third book of Heroes of Olympus series)
* The House of Hades (fourth book of Heroes of Olympus series)
* Blood of Olympus (fifth book of Heroes of Olympus series)
* The Burning Maze (fourth book of Trials of Apollo series)
* The Tyrant's Tomb (fifth book of Trials of Apollo series)
* The Tower of Nero (third book of Trials of Apollo series)
* The Ship of the Dead (second book of Magnus Chase and the Gods of Asgard series)
* The Hammer of Thor (third book of Magnus Chase and the Gods of Asgard series)
* The Throne of Fire (second book of The Kane Chronicles series)
* The Serpent's Shadow (third book of The Kane Chronicles series)
This is not an exhaustive list, as Riordan has also written several other books for younger audiences, as well as some non-fiction works.