Provided are a hardmask composition, a method of forming a pattern using the hardmask composition, and a hardmask formed using the hardmask composition. The hardmask composition includes a polar nonaqueous organic solvent and one of: i) a mixture of graphene quantum dots and at least one selected from a diene and a dienophile, ii) a Diels-Alder reaction product of the graphene quantum dots and the at least one selected from a diene and a dienophile, iii) a thermal treatment product of the Diels-Alder reaction product of graphene quantum dots and the at least one selected from a diene and a dienophile, or iv) a combination thereof.