Maria was the daughter of a farm laborer, Luigi Goretti, and his wife, Assunta Carlini. She showed marked signs of youthful holiness. There were five other children. The family moved in 1896 to Ferriere di Conca, near Nettuno and Anzio in the Roman Campagna. Soon after, Luigi died of malaria. His wife struggled to support the family, receiving much help and encouragement from Maria. She was well known to her neighbors for her cheerful unselfishness and religious disposition.

In 1902, as Maria sat on the front step mending a shirt, an 18-year-old neighbor, Alexander Serenelli, the son of her father's partner, who lived in the same house with the Gorettis, beckoned Maria into a bedroom, but she refused to go. He grabbed her and pulled her in. She struggled and tried to scream, but he choked her. She cried that she would rather be killed than submit. Alexander began to pull her clothes off and struck her with a dagger. She cried out that she was being killed, and he repeatedly stabbed her in the back and ran away.

She was taken to the hospital, but it was clear she would not live. In her last hours she forgave her murderer, whom it was revealed she had feared for a long time but did not want to cause trouble by naming. She died within a day of the attack.

(Another version of the story says that Alexander attacked her when they were working together in the fields.)

Alexander was sentenced to 30 years of penal servitude and for eight years was unrepentant. One night he had a dream in which Maria gathered flowers and offered them to him, and he experienced a change of heart. He served 27 years, and his first act as a free man was to beg forgiveness from Maria's mother. On Christmas Day 1937, Alexander and Maria's widowed mother received Communion side-by-side. He has been cited as an example by those who advocate for the abolition of the death penalty.

In 1947, Maria was declared blessed by Pope Pius XII, who appeared on the balcony of Saint Peter's with Maria's mother and three of her sisters and brothers. In 1950, she was canonized for her purity in front of the largest crowd ever gathered for a canonization. Alexander was still alive. At the time of her canonization, some 30-40 miracles were recorded as a result of her intercession (Attwater, Benedictines, Delaney, Encyclopedia, White).

Maria Goretti is the patron saint of teenagers, particularly girls, and of the Children of Mary (White).