Sebastià has a degree in Catalan philology from Universitat de les Illes Balears, and became known with collection of poems Rafel (1994; Premi Salvador Espriu).

He has also published Apoteosi del cercle (1997), Mula morta (2001) and El benestar (2003).

As a writer, he has published L'extinció (1999), Sara i Jeremies (2002), La pell i la princesa (2005), Nit de l'ànima (2007), Miracle a Llucmajor (2010) and Dos amics de vint anys (2013).

He is the author of the essay about Gabriel Janer Manila L'escriptura del Foc (1998).

His novel Crim de sang has been published in English as Blood Crime (Soho Press, 2016).