Iglesias studied harmony and counterpoint at the Conservatory of his home city, with Francisco Escudero, continuing his education in Paris, where he studied composition and piano, and at Phonos studios, in Barcelona, where he learned electronic music. Afterwards, he created a duo of electronic music with Javier Navarrete, who worked and performed together from 1981 to 1986. He began working in film composition in the 1980s. Iglesias has composed a number of scores for films directed by Pedro Almodóvar, such as "The Flower of My Secret" (1995), "Live Flesh" (1997), "All About My Mother" (1999), "Talk to Her" (2002), "Bad Education" (2004), "Volver" (2006), "Broken Embraces" (2009) and "The Skin I Live In" (2011).