Sebastian Augustinussen (born 6 May 1996) is a Danish handball player who plays for SønderjyskE in the Danish Men's Handball League. He has played several matches for the Danish national junior and youth teams.
In March 2022, he signed a 3-year contract with the Danish club SønderjyskE HÃÂ¥ndbold.
He also participated at the 2013 Men's Youth World Handball Championship in Hungary, winning the title.