Hemvadi (Thai: เหมวดี; RTGS: Hemwadi; 12 January 1892 – 17 October 1972), was the Princess of Siam (later Thailand).

She is a daughter of Chulalongkorn, King Rama V of Siam.

Her mother was The Noble Consort (Chao Chom Manda) Hem Amatayakul (daughter of Lord (Phraya) Dhammasarnniti Vichitbakdi).

After she was born, she was given the name from her father as Mandhana Bhavadi (Thai: มัณฑนาภาวดี).

Later her father changed her name shorter into Hemvadi, on 8 January 1899, while she was 6 years old.