Born in Chicago, Peter Nilsson attended the University of Illinois, where he studied accompanying under John Wustman and voice under Dodi Protero and Mark Elyn. Peter began as repetiteur with the Illinois Opera Center and Bowen Park Opera, and later worked at the Lyric Opera Center for Young American Artists and as accompanist for the Chicago Symphony Chorus, where he worked under Daniel Barenboim, Pierre Boulez, James Conlon, James Levine, Leonard Slatkin and Sir Georg Solti. As repetiteur for the Chicago Symphony Orchestra he worked with, among others, Dale Duesing, Susan Graham, Susan Dunn, Marquita Lister, Anthony Rolfe Johnson, John Tomlinson, and Tatiana Troyanos.
In 1992 Peter moved to Holland, where he is Head of Musical Studies at the Dutch National Opera Academy (Den Haag/Amsterdam) and is a regular guest with the Broadcast Choir and at the Netherlands Opera, where he has worked closely with such conductors as Yves Abel, Marc Albrecht, Daniele Callegari, Paolo Carignani, Riccardo Frizza, Hartmut Haenchen, Ingo Metzmacher, Yannick Nézet-Séguin, Julian Reynolds Carlo Rizzi, en Mark Wigglesworth. Peter Nilsson is also active as accompanist for vocal master-classes, having participated in classes from, among others, Roberta Alexander, Elly Ameling, Diane Forlano, Hartmut Haenchen, Jard van Nes, Anthony Rolfe Johnson, Charlotte Margiono, Nelly Miricioiu, Barbara Pearson, and both series of Masterclasses given by Dame Joan Sutherland and Richard Bonynge at the Britten-Pears School in Aldeburgh.