Initially a violinist, Guérin studied trumpet and cornet at the Paris Conservatory and won a first prize there as a teenager.
He began working professionally in 1947, playing with Aimé Barelli, Django Reinhardt, Don Byas, Hubert Fol, James Moody, Benny Golson, Bernard Peiffer, Fats Sadi, Lucky Thompson, Kenny Clarke, Blossom Dearie, Martial Solal, Michel Legrand and André Hodeir.
He replaced Clark Terry in Quincy Jones's Big Band in 1960.
He worked on the soundtrack to the film Paris Blues in 1961 with Duke Ellington.
With the Kenny Clarke/Francy Boland Big Band With Andre Hodeir With Jimmy Raney With others