His musical training started at the age of five, when Bühler began singing in a choir and also learned to play violin, clarinet, piano, guitar, and drums. His musical career, though, started when he was fifteen in an entirely different genre from lyrical song. He was a member of a cover band and later the lead singer of a heavy metal band called “Conspiracy” when he was seventeen years old in Luzern.

At that time, he was already receiving music lessons at the Academy for School and Church Music. His progress in the field led him to move to Amsterdam in the Netherlands, where he studied voice at Sweelinck Conservatorium with Udo Reinemann, a well-known German baritone. 

Under the private tutoring of Swedish tenor Gösta Winbergh of the Royal Swedish Opera and French tenor Christian Papis, Bühler enriched his classical repertoire. He sang in the choir of the Dutch opera and performed in the Salzburg Festival under the direction of Claudio Abbado. Before joining Il Divo, he was mainly based in the Netherlands, singing oratorios and performing with the Netherlands Opera Gezelschap (NOG). Despite many performances there are only a handful of recordings available of him before Il Divo.

In December 2003, Bühler became a member of the international musical quartet Il Divo along with Carlos Marín (Spain), Sébastien Izambard (France), and David Miller (United States). He had an informal first audition with the group’s creator, Simon Cowell. In Cowell’s office, he simply asked Bühler to sing for him unaccompanied. Impressed by Buhler’s tenor voice, Cowell offered him a place in Il Divo.

Their first album, Il Divo, became a worldwide multi-platinum selling record when released in November 2004, entering Billboard at number four and selling five million copies worldwide in less than a year and knocking Robbie Williams from the number one spot in the charts. Their second album, Ancora, was released on 7 November 2005 in the United Kingdom. Il Divo’s third album Siempre was released on 21 November 2006 in the United States and on 27 November 2006 internationally. Their fourth album, The Promise, was released on 10 November 2008 (world) and 18 November 2008 (US), and shot straight to number 1 in the UK.

Discography:

• Bühler performing in 2008
• The Conspiracy
• Studio album
• 1991 – One to One
• Il Divo
• Main article: Il Divo

Studio album:

• 2004 – Il Divo
• 2005 – Ancora
• 2006 – Siempre
• 2008 – The Promise
• 2011 – Wicked Game
• 2013 – A Musical Affair
• 2015 – Amor & Pasión
• 2018 – Timeless