Antonio Ghislieri was born on January 17, 1504 in the city of Bosco near Alessanderia, Italy. In 1520, He entered as a youth in the Order of Preachers and took the name of Fra Michael. After taking Holy Orders, he took the lectorate and taught theology. He held the office of Prior many times in his convent, becoming famous for his love for others and harshness with himself. In 1551 he became the General Commissioner of the Roman Inquisition. Then in 1556, Pope Paul VI made him bishop of Nepi and Sutri. In the following year he was elevated to the position of cardinal. Pope Pius IV, in 1560, gave him the diocese of Mondovì in Pjemonte.

On 7th January 1566, Antonio was chosen as Pope and took the name of Pius. With the help of St. Karl Borromeo, he gave his entire being to the salvation of souls and the renewal of the life in the Church. Pope Pius V fought harshly with the heretics of his time and preached to defend and to spread the Catholic faith. He brought into practice the Council of Trent: little by little he renewed the Roman Curia; he proclaimed the Roman Catechism (1566); he sought to strengthen the teaching for the clerics by, first and foremost, making the clerics study the Summa Theologica of St. Thomas Aquinas, whom Pius V declared the "Angelic" Doctor - making him the fifth to hold the title of Doctor in the Latin Church (1567); he developed the unity and the renewal of the liturgy, which he revolutionized by proclaiming the Bravery (1568) and the Roman Missal (1570); he praised the unity of the dogmatic tradition between the Oriental and Latin Churches and honoured the brethren of both Churches with four Doctors and liturgical titles.

St. Pius V worked with all his might against the enemies of the faith. Everyone still remembers how much he did to prepare a fleet of ships against the Ottoman forces in the battle at Lepanto on October 7,1571. When he learned that the Christian fleet had won the battle, he announced his belief that the battle was won with the help of Mary of the Rosary. In fact, he ordered her feast in the following year. His holy death happened in Rome on the 1st of May, 1572. Pope Clement X on May 1, 1672, elevated him to the alters, through the title of blessed. He was then canonized on the 22nd of May 1712 by Pope Clement XI.

His remains are found for the veneration of the faithful in the basilica S. Maria Maggiore, Rome.

The Maltese venerate St. Pius V as a father who took care of his children. This saint gave a great amount of help to the building of the new Capital City of Malta - Valletta. Because of this, the Maltese Dominican Province chose him as its Patron saint and celebrate his day as a feast on April 30.