Is it normal to wear nothing under a hoodie?
Depends.It depends
Yes, plenty of people wear a hoodie without a shirt underneath, especially at home or when they want fewer layers. Whether it feels appropriate in public depends on the setting, the hoodie, and your comfort.
It’s a perfectly ordinary comfort choice—some people like the feel of the hoodie on their skin, want to stay warm without layering, or just don’t feel like putting on a shirt. Other people would feel too exposed or get sweaty, so it’s really personal preference.
In public, think about whether the hoodie is opaque, fits securely, and suits the place you’re going. If it’s clean and you’re comfortable, there’s no special rule saying you need a shirt underneath.