[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 attended many conferences in France and abroad, mainly in Italy, where the city of Ravenna elected him an honorary citizen in 1986.

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