Sultanah Hajah Bahiyah binti Almarhum Tuanku Abdul Rahman (Jawi: سلطانة حاجة باهية بنت المرحوم توانكو عبدالرحمن; 24 August 1930 – 26 August 2003) was the Sultanah of Malaysian State of Kedah from 1958 until her death in 2003 and served as the fifth Raja Permaisuri Agong of Malaysia from 21 September 1970 until 20 September 1975.

She was the eldest daughter of Tuanku Abdul Rahman and his third wife Tunku Kurshiah, the Yang di-Pertuan Besar and the Tunku Ampuan Besar of Negeri Sembilan, who were then elected as the first Yang di-Pertuan Agong and Raja Permaisuri Agong of Malaysia.

She later furthered her studies in the United Kingdom and received a degree in Social Science from University of Nottingham.

She died in her sleep at 12:23 pm of cancer and old age on 26 August 2003 at Istana Kuala Cegar, Alor Setar.

In 1973, King Bhumibol Adulyadej of Thailand awarded her the Grand Cross of the Order of Chula Chom Klao.