Eiichiro Oda was born on January 1, 1975, in Kumamoto, Japan. He decided at the age of four that he wanted to become a manga artist to avoid having to get a conventional job. His early work was heavily influenced by Akira Toriyama, the creator of Dragon Ball, and his interest in pirates was sparked by the animated series Vicky the Viking.

Oda began his professional career while still a teenager. At 17, his work Wanted! earned him a place as a finalist in the prestigious Tezuka Award. This achievement led to work at Weekly Shōnen Jump magazine, where he served as an assistant on several series, including Nobuhiro Watsukis Rurouni Kenshin. During this period, he drew two pirate-themed one-shot stories called Romance Dawn in 1996, which featured a protagonist named Monkey D. Luffy and served as a prototype for his later masterpiece.

In 1997, Oda began serializing One Piece in Weekly Shōnen Jump. The series became a global phenomenon, holding the Guinness World Record for the most copies published for the same comic book series by a single author. With over 523 million copies in circulation worldwide, One Piece is the best-selling manga in history. Individual volumes have repeatedly broken Japans initial print run records, with volume 67 receiving a first printing of over 4 million copies. In 2013, the series won the Grand Prize at the 41st Japan Cartoonists Association Awards.

As the original creator, Oda has been deeply involved in the numerous anime adaptations of his work. For the tenth theatrical film, One Piece Film Strong World, he personally wrote the story, produced over 120 character and setting designs for the animation team, and insisted on the musical act for the theme song. He served in similar creative roles for subsequent films, including executive producing and providing character designs for Z, Gold, Stampede, and Red. His one-shot manga Monsters from 1994 was adapted into the anime Monsters: 103 Mercies Dragon Damnation. Oda also collaborated with Akira Toriyama to create the crossover special Dream 9 Toriko & One Piece & Dragon Ball Z Chō Collaboration Special!! and the one-shot manga Cross Epoch. Other anime projects based on his original work include Koisuru One Piece, One Piece 3D Gekisō! Trap Coaster, and One Piece 3D: Mugiwara Chase.

Oda is known for his rigorous work schedule and perfectionism, reportedly sleeping only about three hours per day during a typical work week. He has publicly acknowledged other manga artists as both friends and rivals, including Masashi Kishimoto, the creator of Naruto, and has included tributes to their work in his own manga. Following a damaging earthquake in his home prefecture of Kumamoto in 2016, Oda donated 800 million yen to aid recovery efforts, with part of the donation made under the name of his protagonist, Monkey D. Luffy.