After receiving several prizes in singing at the Conservatoire de Bordeaux, he started at the age of 22 years at the Grand Théâtre de Bordeaux in the role of Des Grieux in Manon, an opera by Jules Massenet. They totaled more than 10,500 performances and recorded many records in their careers. He was a prolific performer at the Théâtre Mogador in Paris.
Merkès was married to violinist and singer Paulette Merval.
Their son, Alain Merkès, also pursued a career as singer under the name Alain Valmer. Marcel died in Pessac.
, debut of performance is given:
Rêve de Valse by Oscar Straus – Théâtre Mogador, Paris, 22 March 1947
Imperial Violets by Vincent Scotto – Théâtre Mogador, Paris, 31 January 1948
Annie du Far-West by Irving Berlin – Théâtre du Châtelet, Paris, 19 February 1950
Rose-Marie by Rudolf Friml – Théâtre de l"Empire, 12 May 1950
Louisiana Veuve joyeuse by Franz Lehár – Théâtre Mogador, Paris, 17 November 1951
Les Amants de Venise by Vincent Scotto – Théâtre Mogador, Paris, 5 December 1953
Les amours de Don Juan by Juan Morata – Théâtre Mogador, Paris, 23 December 1955
Michel Strogoff by Jack Ledru – Théâtre Mogador, Paris, 5 December 1964
Vienne chante et Danse by Johann Strauss II and Jack Ledru – Théâtre Mogador, Paris, 25 November 1967
Douchka by Georges Garvarentz and Charles Aznavour – Théâtre Mogador, Paris, 4 October 1973
Princesse Czardas by Emmerich Kálmán, Avignon 1979–1982.