Oscar Verhaar was born in Rotterdam, The Netherlands, and started his musical career as a treble in the Rotterdam Boys Choir, with whom he sang many solos both in The Netherlands and abroad (Austria, France, Switzerland, Russia and the US, among others). In June 2012 Oscar completed the Early Music Singing Master at the Royal Conservatory The Hague, where he studied with Michael Chance, Jill Feldman, Lenie van den Heuvel and Peter Kooij. In addition, Oscar studied with Lydia Vierlinger in Vienna and took masterclasses with Ian Bostridge, Carlos Mena, Deborah York, Eric Mentzel and Kees Boeke.
In September 2014, Oscar was the only male finalist of the Concours de Chant Baroque de Froville in France. In 2010 Oscar won the first prize of the Austria Barock Akademie. In autumn 2015, Oscar was selected as one of the Classical Talents at the Dutch BUMA Classical Convention and in 2017 he became a Laureate of the Fondation Royaumont.
Since 2002 he has been performing as a soloist in the oratorio repertoire, singing the major works by Bach, Handel, Vivaldi and others. In 2008 Oscar made his debut at the Festival Oude Muziek Utrecht in a recital with music by Constantijn Huygens in the Fabulous Fringe series. On the opera stage he has performed in Dido and Aeneas by Henry Purcell, Venus and Adonis by John Blow and Benjamin Britten's Abraham and Isaac. In October 2010, he had great success performing the role of Speranza in Monteverdi's Orfeo for the Dutch Opera Studio, staged by Pierre Audi.
Oscar has been a member of the Ascoli Ensemble, a vocal ensemble specialised in medieval music, since 2009 and performed with them in Italy, Boston and New York. He is also the singer of the ensemble astrophil&stella, with whom he performs renaissance music.
In 2014 an 80 minute-long documentary about Oscar's time at the Royal Conservatory and his cooperation with his former teacher Geert van den Dungen was broadcasted on Dutch national television. This film, The Voice of the Master, was directed by Hester Overmars.
More recently Oscar sang at the festivals Laus Polyphoniae Antwerp, Early Music Festival Budapest and in The Netherlands at Opera Festival Rotterdam and Wonderfeel. In 2014 his first solo CD appeared with Quintone records, featuring music by Constantijn Huygens and his contemporaries such as Caccini, Kapsperger and Monteverdi.