Formal:
* Ты мой/моя/моё. (Ty moy/moya/moyo) - This is the most direct and formal way to say it. You would use this for someone you respect or don't know well.
* Ты принадлежишь мне. (Ty prinadlezhish mne) - This means "You belong to me" and is a more possessive and less common way to say it.
Informal:
* Ты мой/моя/моё. (Ty moy/moya/moyo) - This is the same as the formal version, but it's more casual. You would use it with friends and family.
* Ты мой/моя/моё (любимый/любимая). (Ty moy/moya/moyo lyubimyy/lyubimaya) - This is a more affectionate way to say it, meaning "You are my (beloved)."
Romantic:
* Ты мой/моя (единственный/единственная). (Ty moy/moya edinstvennyy/edinstvennaya) - This means "You are my only one" and is a romantic way to say "You are mine."
* Ты моя судьба. (Ty moya sud'ba) - This means "You are my destiny" and is a very romantic way to say it.
Important note: It's important to be aware of the context and who you're talking to before using any of these phrases. The meaning can be quite different depending on the context and relationship between the speaker and the listener.