- Morgan Davies (The Evil Dead) as Koby
- Ilia Isorelýs Paulino (The Sex Lives of College Girls) as Alvida
- Aidan Scott (Action Point) as Helmeppo
- Jeff Ward (Hacks) as Buggy the Clown
- McKinley Belcher III (Ozark) as Arlong
- Vincent Regan (Troy) as Monkey D. Garp
The upcoming first season of the series will have a total of 10 episodes, with the first episode of the series confirmed to be titled "Romance Dawn", the manga's first arc that introduced us to Monkey D. Luffy and his first crewmate, the pirate hunter Roronoa Zoro. As previously reported, the series will be produced by Marty Adelstein and Becky Clements of Tomorrow Studios (Cowboy Bebop, Snowpiercer), with Adelstein stating that the series will start with the very first arc of the series, the East Blue Saga. He also stated that the series promises to create "a true One Piece" after he discussed the project with series creator Eiichiro Oda personally, who also serves as the show's executive producer. Oda previously stated that he will "never betray the fans who have supported me for 20 years."
In addition, Deadline confirmed that Steven Maeda (Lost, The X-Files) and Matt Owens (Agents of S.H.I.E.L.D., Luke Cage) will now serve as both co-showrunners and executive producers. One Piece is a co-production between Netflix and Tomorrow Studios, with Netflix handling physical production.