In 2003 graduated from the Conservatorium van Amsterdam with David Wilson-Johnson. In 2005 he graduated from the New Opera Academy Amsterdam. In 2007 he represented the Netherlands at the BBC Cardiff Singer of the World.
He was subsequently a member of the Netherlands Opera Studio and the Atelier Lyrique (Opéra National de Paris). In 2008 he made his debut at La Monnaie Brussels as Le Berger (Pelléas et Mélisande), at Teatro Real in Madrid as Frére Léon (St. François d'Assise), at Opéra Royal de Wallonie Liège as Il Conte (Le nozze di Figaro) and at Opéra National du Rhin Strasbourg as Falke (Die Fledermäuse).
From 2009 until 2014 he was a full member of the Opera House in Dessau where he sung amongst others parts such as: Papageno (Die Zauberflöte), Heerrufer (Lohengrin), Silvano (Un ballo in maschera), Maximilian (Candide), Pietro (La muette de Portici), Zurga (Les pêcheurs de perles), Belcore (L'elisir d'amore). In 2014 he created Schemariah (Hiob by Erich Zeisl after Kafka’s novel) at Bayerische Staatsoper. In 2016 the singer took part in the world première of Pascal Dusapin's Penthesilea (as Messager) at La Monnaie. The meeting with Dusapin led to Witholt's engagement by the Sydney Festival 2016 to perform the main male part in his opera Passion, for which he was nominated for the Helpmann Awards (Australia).
In the concert repertoire of the singer are compositions of the cantata-oratorio genre, including Bach's cantatas, performed with the Concertgebouw Chamber Orchestra, as well as Mahler's vocal cycles, including Lieder eines fahrenden Gesellen (Songs of a Wayfarer), presented at the Opéra National de Paris and at the Klarafestival.