Mabo was born as Eddie Koiki Sambo. He changed his surname to Mabo when he was adopted by his mother's brother, Benny Mabo. He was born on Mer (Murray Island) in the Torres Strait between Australia and Papua New Guinea. He worked on a number of jobs before becoming a gardener with James Cook University in Townsville, when he was 31 years old. The time he spent on the university campus had a major impact on his life. In 1974, Mabo was surprised to learn that his family did not legally own the land they lived on. In a conversation with Noel Loos and Henry Reynolds, he learned that legally that land belonged to the Crown.