He entered the Society of Jesus in 1817 and after teaching for eleven years at the Jesuit College at Brieg, Switzerland, he became in 1840 a missionary and catechist in Köthen, Germany. With Father Rohe, S.J., he established at Lucerne in 1845 the academy of St. Charles Borromeo. In 1847 he left Switzerland, which had become hostile to Jesuits.
After that he was chiefly engaged in giving missions in Germany.
As a catechist in Köthen he felt the lack of a good catechism, and was encouraged by his superior, Fr. Devis, to compose one. As a model he took the Mainz catechism of 1842 and made use also of other good textbooks, notably of Bossuet's catechism. He completed his first catechism, called "Katholischer Katechismus oder Lehrbegriff" in 1847.
In 1848 it appeared anonymously at Ratisbon and immediately won approval. Bishop Blum of Linsburg introduced it officially into his diocese the same year; the following year the bishops of Trier and Hildesheim did likewise for their dioceses. In 1850 the Bavarian bishops resolved to introduce a common catechism for the entire kingdom, and accepted Deharbe's catechism, which was then introduced in 1853. Other German dioceses adopted it as follows: Cologne, 1854; Mainz and Paderborn, 1855; Fulda, 1858; Ermland, 1861; Culm, 1863; Gnesen-Posen, 1868. At the same time it spread outside of Germany, in Switzerland, Austria-Hungary, and the United States. It was translated in 1851 into Magyar, then into Bohemian, Italian, and French; into Swedish and Marathi, 1861; into Polish and Lithuanian, 1862; into Slovenian, 1868; into Danish, 1869; and later into Spanish and Portuguese. It was reintroduced into Bavaria in 1908. In a revised form, Austria adopted it in 1897.
Deharbe himself prepared and published at Ratisbon four extracts of his first work, titled
He preserved catechetical tradition but abandoned the division of Peter Canisius, arranging the text-matter under chapters on Faith, Commandments, and Means of Grace.
His other works, all published at Ratisbon, are: