Yes, online poker is legal in the United States, albeit only in certain states. As of early 2024, only six states have legalized online poker Nevada, Delaware, New Jersey, Pennsylvania, West Virginia, and Michigan.
Real money online poker is legal and available in New Jersey, Pennsylvania, Nevada, Michigan and Delaware. It's also legal in Connecticut and West Virginia, but yet to go live there. The top NJ online casinos and Pennsylvania sites are the leaders in online poker.