Roblox provides its users with a wide range of options for personalizing their avatar or character. Players can purchase or acquire free items such as clothing, accessories, and other cosmetics.

Steps for altering your avatar’s appearance in every Roblox experience, from adding and removing items to changing your skin color and gender.

Much like most things on Roblox, you will be making this yourself from scratch, so you'll need to design a t-shirt in an image and then upload it to Roblox.