Alan entered the Dominican Order at Dinan in the diocese of Saint- Malo in Brittany when religious life in the region was at a low point. He migrated from there to the Netherlands, where he preached, wrote, and organized. He was extraordinarily devoted to the Blessed Mother and never missed an opportunity to preach the Rosary.

Alan is supposed to have had a vision of the Blessed Mother, who encouraged him to revive devotion to the Rosary. Thus, he preached on it and Saint Dominic, especially in Germany. He founded the Confraternity of the Psalter of Jesus and Mary (now called the Confraternity of the Rosary) in Douai, France, in 1470. The first printed manual of the Confraternity of the Rosary, which explained how to say it and laid out the original 15 mysteries, was published in Cologne in 1476, after Alan's death.

Saint Dominic appeared to Blessed Alan as well and told him of the great results of his ministry:
-he had preached the Holy Rosary unceasingly,
-his sermons had borne great fruit and
-many people had been converted during his missions.

He said to Blessed Alan: "See the wonderful results I have had through preaching the Holy Rosary! You and all those who love Our Lady ought to do the same so that, by means of this holy practice of the Rosary, you may draw all people to the real science of the virtues." This is what inspired Blessed Alan de la Roche to work so hard to restore the devotion to the Holy Rosary, originally established by Saint Dominic.

Blessed Alan died at Zwolle in Holland, September 8, 1475.