Udvarhely (German: Oderhellen) was an administrative county (comitatus) of the Kingdom of Hungary.

The capital of the county was Székelyudvarhely (now Odorheiu Secuiesc).

In 1920, by the Treaty of Trianon, the county became part of Romania until 1940 when, by the Second Vienna Award, much of its territory was reassigned to Hungary.

After the end of World War II it became again part of Romania.

In the early 20th century, the subdivisions of Udvarhely county were: