[2] After attending the École nationale supérieure des arts décoratifs to complete his education, Frossard began a career in journalism as a cartoonist and columnist.

Raised as an atheist, at the age of 20 Frossard converted to Catholicism and was baptized in the chapel of the Sisters of Adoration on 8 July 1935.

He was interned in the "Jew Shed" of Montluc prison and was one of seven survivors of a massacre in Bron on 2 August 1944, in which 72 were killed.

He was awarded the Legion of Honor and promoted to the rank of officer by General Charles de Gaulle.

In 1990, Pope John Paul II awarded him the Grand Cross of the Equestrian Order of the Holy Sepulchre.