Van der Walt, one of the first South Africa opera singers to achieve international success, studied at the University of Stellenbosch and debuted at the Kapstadt Opera House. He won an international Mozart competition in Salzburg in 1981 and debuted at Covent Garden in 1985 as Almaviva in Rossini's The Barber of Seville. In the years since, he performed at La Scala, the Vienna State Opera, the Salzburg Festival, and the Metropolitan Opera.

His Mozart roles included Belmonte in The Abduction From the Seraglio, Ferrando in CosÐ fan tutte, and Tamino in Die Zauberfl‹te; he also sang Rom_o in Gounod's Rom_o et Juliette, Des Grieux in Massenet's Manon, and Tonio in Donizetti's La Fille du r_giment.