Bl. Agnellus was born in Pisa in 1195 of the prominent family, the Agnelli. This similarity to the upbringing of St. Francis makes it no surprise that Agnellus was approached by St. Francis himself and invited to join his Order. He lived a life of holiness, his purity, wholesomeness and devotion to improving the world around him had great impact on the world around him. Agnellus understood the value in learning and though not extremely learned himself, Agnellus sought to further the education of the monks and friars around him. This was how the founding of Oxford, in England, came about. His kind heart made him a friend and confidant to rulers and diplomats.
In his early youth, Agnellus was personally received into the Seraphic Order by St. Francis of Assisi, during the latter's sojourn in Pisa. After being sent to Paris by St. Francis, where he became Custos, Agnellus built a friary in the city. He then returned to Italy, was present at the first Chapter of Mats of the Order, and thence was sent by St. Francis to establish the Order in England. He and his party landed with nine other friars, who were graciously sent from France under the orders of the friars at Fecamp, Dover, on September 10, 1224. It was not easy for these brave friars, as the winter of 1224 was extremely harsh, and any food they ate had to be boiled to unfreeze. However, they did not let the conditions get their spirits down. The friars traveled on through the cold, always cheerful and believing they were filled with the Holy Spirit of God. Finally, months after the first cold winter, the friars found a place to shelter in. Their arrival was honored by Pope Honorious III. When the friars arrived, the Archbishop of Canterbury was expecting them with open arms. Everywhere the friars went they were treated with respect and honor. Agnellus and his followers soon became known for their humble manner, extreme prudence, and desire for no material items but what was necessary to survive.
Throughout his life, Agnellus would never allow expansion to the friars quarters, or to the university other than what was absolutely necessary. This example was kept up for a little more than a decade, until Haymo of Faversham began the expansion of the English order's holdings so that they would be able to provide for themselves rather than depend on others' charity. Yet, despite his extreme frugality, Agnellus had a gentle way about him. It was this gentleness that made it possible for him to negotiate a truce with King Henry III of England. The English Franciscan Order secured a house there and subsequently played a large role in the establishment of the University of Oxford soon after.
Agnellus established a school for the friars at Oxford, which helped in the development of the theology school at the university. He was not himself a scholarly man, but understood the importance of learning and knowledge. Therefore, Agnellus had great influence in affairs of the state. King Henry befriended the friar out of admiration for his wholesome, pure, ambitious attitude towards life. This resulted in Agnellus' becoming heavily involved in efforts to avoid a civil war between the King and the Earl Marshal, who had aligned himself for war with the Welsh. Shortly afterwards, Agnellus contracted a fatal illness and died abruptly on 7 May 1236. His remains were buried at Oxford. His feast is kept on March 13.