Sonia, Sonja or Sonya, can be:
- Sonia (name), a given name for women
- Sonia (actress), Indian movie actress in Malayalam and Tamil movies
- Sonia (singer), British pop singer Sonia Evans
- Sonia, pen name of Ottavia Vitagliano (1894–1975), an Italian writer
- Sonia, code-name of Ursula Kuczynski, also known as Beurton, a spy for the USSR
- Queen Sonja of Norway (born 1937)
- Sonia Ben Ammar, French fashion model, actress and singer known as SONIA
- Sonia people, an ethnic group on the Great Papuan Plateau of Papua New Guinea
- Sonia, a code name for the Mitsubishi Ki-51, bomber airplane
- SONIA, Sterling OverNight Index Average, a financial market rate
- Sonia (album), a 1991 album by Sonia Evans
- Sonia (1921 movie), a 1921 British silent movie
- Sonja (1943 movie), a 1943 Swedish movie directed by Hampe Faustman
- Sonia (genus), a genus of moths
- M/V Sonia, a passenger ferry