Sea of Thieves is a pirate-themed action-adventure cooperative multiplayer game played from a first-person perspective. The game features cross-platform play between Windows-based personal computers and Xbox One video game consoles. A group of players travel and explore an open world via a pirate ship and assume different roles such as steering, hoisting sails, navigation, and firing cannons. Players embark on quests, collect loot and engage in combat with other players. Sea of Thieves is a shared game world, which means groups of players will encounter each other regularly throughout their adventures. The game has a cartoonish art style and an exaggerated physics engine that allow players to perform stunts, like being shot out of ship cannons.

Players can collect coins by completing missions called voyages, taking loot from other ships, or raiding a skeleton fort that contains large amounts of gold. The gold can be used for purchasing everything from re-skinned weapons to new hulls and sails for the ship. These items are cosmetic and do not affect combat. The weapons are given to the player at the start of the game, and have five rounds of ammo before needing to find an ammo box to restock. The four usable weapons are a flintlock, a blunderbuss, a long rifle, and a sword. Two weapons can be carried at once.