The world of One Piece is thrown into a golden age of piracy following the final words of the legendary Pirate King, Gol D. Roger. Just before his execution, Roger announces that his greatest treasure, the mysterious One Piece, is hidden somewhere in the world and is available for anyone to claim. This declaration inspires countless individuals to set sail, including a young boy named Monkey D. Luffy from the quiet East Blue village of Foosha. Inspired by his idol, the pirate Red-Haired Shanks, Luffy dreams of becoming the next Pirate King. As a child, he accidentally eats a Gum-Gum Fruit, a mysterious Devil Fruit that grants his body the properties of rubber but also takes away his ability to swim. Years later, a determined but inexperienced Luffy sets out to sea on a small boat, determined to gather a crew and find the One Piece.

Luffy’s journey begins as he builds his crew, the Straw Hat Pirates, named after the treasured hat given to him by Shanks. His first recruit is Roronoa Zoro, a powerful and disciplined master of three-sword style who aims to become the world's greatest swordsman. They are soon joined by Nami, a skilled navigator and thief who dreams of mapping the entire world; Usopp, a marksman and inventive liar who aspires to become a brave warrior of the sea; and Sanji, a chivalrous and passionate cook searching for the legendary All Blue, a sea where all the oceans of the world meet. Together, this unlikely crew ventures into the treacherous Grand Line, a dangerous and unpredictable ocean strip that defies logic and is home to the world's most powerful pirates.

As Luffy and his crew travel from one bizarre island to the next, they confront a wide array of enemies and uncover the dark secrets of the world. They protect kingdoms from tyrants like the sinister Sir Crocodile in the desert country of Alabasta and challenge the tyrannical gods of the sky island of Skypiea. The crew grows larger and stronger, adding the reindeer doctor Tony Tony Chopper, the archaeologist Nico Robin, the cyborg shipwright Franky, the skeletal musician Brook, and the fish-man helmsman Jinbe. Their adventures place them in direct conflict with the World Government, a powerful global organization that rules the seas with its immense naval forces and secret intelligence agencies. The Straw Hats also face rival pirates, including the enormous and monstrous crew of the Yonko, the four most powerful pirate captains in the world.

Key narrative arcs test the crew's loyalty and resolve. The Water 7 and Enies Lobby arcs force them to declare war on the World Government to save Robin, who is targeted for her ability to read ancient texts that could reveal a lost century of history. After a devastating defeat at the hands of the Navy, Luffy learns to use Haki, a latent spiritual power that allows him to sense, resist, and overpower his enemies. Following a two-year training time-skip, the crew reunites and dives into the second half of the Grand Line, known as the New World. There, they challenge the Yonko, forming alliances and leading massive raids to liberate kingdoms, culminating in a climactic battle on the island of Wano to defeat Kaido, the strongest creature in the world. From fighting oppressive warlords to clashing with the top tiers of the navy and even forming temporary truces with rivals, Luffy continues his relentless pursuit of freedom, adventure, and the ultimate treasure that will crown him the Pirate King.