Born in Ixelles Christian Denayer grew up in post-war Belgium, and initially focused on becoming a teacher. But he eventually chose an artistic career, making his first drawings for advertisements. Because of his passion for cars, he became Jean Graton's assistant when he was 17 years old. He cooperated on about 10 albums of Graton's Formula 1 series 'Michel Vaillant'. In addition, he made gag pages for Junior, short stories for Tintin with Yves Duval, as well as 'Alain Bercy' in Formule 1 (1967) and 'L'Écurie Europe' in J2 Jeunes. He later worked as the assistant of Tibet on 'Ric Hochet'. Tibet encouraged him to create a comic of his own, which resulted in 'Yalek', a comic series scripted by André-Paul Duchâteau and published in Le Soir Jeunesse from 1969.
For the same paper and with the same writer, he then produced 'Alain Chevallier', which gave him another chance to draw racing cars. Initially created under the joint pseudonym Cap, Denayer and Duchâteau continued the series in the magazine Tintin in 1976. A year earlier, Denayer and Duchâteau had already launched 'Les Casseurs' in Tintin, a series that was later retitled to 'Al et Brock'.
Denayer and Duchâteau were additionally briefly present in Spirou with the comic 'Patrick Leman' and the illustrated text riddle stories 'L'Inspecteur Spirou' between 1970 and 1977. While still working on his police series 'Al et Brock', Denayer created the SF saga 'Gord' with Franz for Lombard in 1986.
By 1989 he was hired by publisher Claude Lefrancq to draw 'T.N.T.', a series of three books written by Loup Durand and Duchâteau, based on the oeuvre of novellist Michaël Borga. He also remained active for Lombard, producing both script and artwork for five books of the teen comic 'High School Generation' between 1994 and 1998. In 2000, he started working with Jean Van Hamme on the hit detective series 'Wayne Shelton', published by Dargaud. After two episodes, Van Hamme was succeeded by Thierry Cailleteau, but he returned as the series writer in 2010.