The Crimson Sign is an interactive block used to display text and communicate messages in the world. It is crafted using 6 Crimson Planks and 1 Stick in a 3×3 crafting grid and can be placed on the ground as a standing sign or attached to blocks as a wall sign. A Crimson Sign allows players to write up to four lines of text. Signs can be edited after placement, allowing text to be changed without breaking the sign. Glow Ink Sacs can be applied to make the text glow in the dark, while Dyes change the text color.

A Crimson Sign can be waterlogged, allowing it to be placed underwater while remaining readable. It is commonly used for labeling storage, marking locations, and creating in-game messages. A Crimson Sign can be mined instantly by hand or with any tool.