The Celestial Portal is constructed by using the Portal Paraphernalia on the Florid Postern, and adding a Purple Moonlens and twenty Moon Rocks to it. Items can be added incrementally, and adding more than what is required will cause the excess to fall to the ground. Items committed cannot be removed.
When offered a Moon Rock Idol, the Celestial Portal will send the player back to the Character selection screen. When leaving the world, all items in the player's Inventory will be dropped automatically. Upon choosing a new character, the player will be transported back to the same world, keeping their Day count and Map exploration progress, along with any prototyped Crafting recipes and any adopted Critters.
Additionally, the Celestial Portal serves the same functions as the Florid Postern. It still marks the server's spawn point, and, if the server is set to Endless Mode, it can be used by a Ghost Characters to resurrect at a cost of 25% of their maximum Health (this penalty can be reversed by using Booster Shots).
- Players should not build a Celestial Portal in the Caves since it does not work as it should down there.
- WX-78 will lose their upgrade level and drop some Gears upon offering Moon Rock Idol to Celestrial Portal. The amount of dropped Gears is a random number between 1/3 and 1/2 of the upgrade level (a number of eaten Gears, but not more than 15). This means that most of the Gears used for upgrades will be permanently lost.
- When it was first introduced in the Celestial Update, changing characters at the Portal used to reset the player's map, day count, and crafting recipes. This is no longer the case as of update 288118.
- It should be noted that, since Wickerbottom is able to craft Science Items with a lower tier Crafting Station than other Characters from the start, she never properly "learns" those recipes, thus even if the player had crafted any of those recipes, it would appear "locked" when changing from Wickerbottom to another character.
- The Celestial Portal gives off a small amount of light at night, but is not an appropriate light source to ward off Charlie.
- The Portal shows different stages of progress based on how close its construction is to being finished.
- If Woodie offers a Moon Rock Idol to the Portal, Lucy the Axe will turn into a regular Axe when returning as a different character.
- Each character has an unique quote before the game returns to the character selection screen.