Harju is a Finnish surname. Notable people with the surname include:
Arsi Harju (born 1974), Finnish shot putter Beata Harju (born 1990), Finnish voice actress Chris Harju (born 1957), American rugby union player Johan Harju (born 1986), Swedish ice hockey player Jori Harju (born 1964), Finnish admiral Juha Harju (born 1981), Finnish heavy metal musician Matti Harju (born 1943), Finnish ice hockey player Mirella Harju (born 1982), Finnish racing cyclist Venla Harju (born 1990), Finnish orienteer