Born Jacopo dei Benedetti, he was a member of a noble family. He studied law in Bologna and became a successful lawyer. At some point in his late 20s, he married a young noblewoman, named Vanna according to some accounts, who was a pious and generous woman. Due to his reputation as a worldly and greedy man, she took it upon herself to mortify her flesh in atonement for his behavior.
Not long after their wedding, Benedetti urged his wife to attend a public tournament. In the course of the spectacle, she was killed when part of the stand in which she was sitting gave way. Rushing to her side, he discovered that she had been wearing a hairshirt. Shocked, he realized that she had performed this penance for his sake.
The Piazza del Popolo in Todi, where Jacopone crawled around on one occasion
Benedetti gave up his legal practice, gave away all his possessions and from about 1268 lived as a wandering ascetic, joining the Third Order of St. Francis. During this period, he gained a reputation as a madman, due to his eccentric behavior, acting out his spiritual vision, earning him the nickname he was to embrace of Jacopone (Crazy Jim). Examples of this behavior included appearing in the public square of Todi, wearing a saddle and crawling on all fours. On another occasion, he appeared at a wedding in his brother's house, tarred and feathered from head to toe.
After about ten years of this life, Benedetti sought admission to the Friars Minor, but they were reluctant to accept him due to his reputation. He soon composed a beautiful poem on the vanities of the world, which led to his admission into the Order in 1278. He chose to live as a lay brother.
By this time, two broad factions had arisen in the Franciscan Order, one with a more lenient, less mystical attitude and one being more severe, preaching absolute poverty and penitence (known as the "Spirituals" or Fraticelli). Jacopone was connected with the latter group and in 1294 they sent a deputation to Pope Celestine V to ask permission to live separately from the other friars and to observe the Franciscan Rule in its perfection. The request was granted. But Celestine resigned the papacy before action was taken and was succeeded by Pope Boniface VIII, who opposed the more rigorous views. During the struggle that followed, Jacopone publicized the Spirituals' cause by writing verses highly critical of their opponents, the Pope included. When two brother-cardinals, the Colonnas, sided with the Spirituals and with the king of France against Pope Boniface, and Fra Jacopone gave his support to the Colonnas, politics and even war entered upon the scene. The Pope excommunicated them. A battle between the two rival parties ensued, ending with the siege of Palestrina and the imprisonment and excommunication of Jacopone in 1298. He was freed in 1303 upon the death of Boniface, having been specifically excluded from the Jubilee Year of 1300 by papal bull.
Broken and in poor health, Jacopone retired to Collazzone, a small town situated on a hill between Perugia and Todi, where he was cared for by a community of Poor Clares. His condition deteriorated toward the end of 1306, and he sent word requesting that his old friend, John of La Verna, come to give him the last rites. John arrived on Christmas Eve and comforted him, as he died about midnight.
Jacopone's body was originally buried in the monastery church. In 1433 his grave was discovered and his remains transferred to a crypt in the Franciscan Church of San Fortunato in Todi.