Sebbens, one of six children, was born and raised in Darwin, Northern Territory. Her father is a former long-distance coach driver from Sydney of English descent and her mother, Annarella, an indigenous education worker from Broome, Western Australia is of Jabirr Jabirr and Baada heritage. She is the niece of Australian music Composer and Playwright Jimmy Chi and cousin of Writer and film Director Mitch Torres. As a child, Sebbens wanted to become a palaeontologist or an Astronaut but at the age of thirteen she saw indigenous Actress Deborah Mailman in the film Radiance (1998) and was inspired to pursue acting. Sebbens graduated from Darwin High School in 2001 and four years later, at age nineteen, was chosen to participate in "SPARK"; a theatre mentorship programme established by the Australia Council for the Arts. At age twenty she was accepted into the Western Australian Academy of Performing Arts (WAAPA) where she completed a one-year course in Aboriginal Theatre. Upon completing her studies at WAAPA Sebbens successfully auditioned for a place at the National Institute of Dramatic Art (NIDA) studying acting full-time for three years.

Sebbens secured a role in The Sapphires (2012), a film based on the stage show of the same name. It was directed by Wayne Blair and also starred Deborah Mailman, Jessica Mauboy, and Miranda Tapsell. Sebbens played the role of Kay McCrae, one of four Indigenous Australian Singers "who travel from a mission in Victoria to Vietnam to sing for American troops". The cast attended the film's premiere at the 65th Annual Cannes Film Festival in Cannes, France on 20 May 2012.