Yes! Online multiplayer was added in version 1.5, released in 2022. You can access it via the Multiplayer button on the main menu.

You can play with anyone else who owns the game. You can play as Spirits from any expansion DLC you own. The Spirit Leader can select other game content (Adversaries, Scenarios, Island Boards, etc) based on the DLC they own.

Since Spirit Island is a cooperative game with no hidden information, you can also play online using screen sharing (such as Steam Remote Play Together). Check out our guide!