He studied at the Gallio College in Como. On May 26th, 1886 he was ordained as a priest. On that solemn day, he wrote that his plan was to “be a sword of fire in the ministry of charity”. During the early life of his priestly ministry, he took many efforts to help his people, becoming “everything for everyone”. He dedicated himself zealously to young people in helping them, in their schooling and revitalising Catholic Action. 
He was in contact with St John Bosco   (1815-1888). At the time fascinated by the Salesian charism, he tried opening a College for the young but the operation didn’t go ahead.   However, he wanted to have a experience with Don Bosco and from1875 he lived in the  Salesian family.  He was in charge of the “Saint Aloysius” Oratory in Turin and soon after was appointed Rector of the “Dupraz” College in Trinità (Cuneo).   He remained in the Salesian Congregation for just three years, because the Lord had arranged different plan: Otherwise the bishop of Como in fact called him back to the diocese.   Louis had no fear of defending young people and the poor even in front of the powerful and the politicians.  
                         

In 1871, Fr. Coppini, a young pious Priest had founded the Pious Union of Daughters of Mary Immaculate. On June 28, 1878, the bishop had authorized Father Coppini to establish a religious community and consecrated its members, Sr. Marcelina, Sr. Clare, Sr. Rosa, Sr. Giacinta and Sr. Agnes.  On 1st July 1881, Don Carlo Coppini died in the town of Pianello Lario, leaving behind a small home for orphans and the aged, which he had entrusted to the care of a group of young women, which he called ‘The Pious Union of the Daughters of Mary’, under the patronage of St. Ursala and St. Angela Merici. No one seemed willing to assume the burden of carrying on Father Coppini’s work until the bishop remembered Father Guanella, whom he thereupon sent to Pianello.

In five years with the cooperation of the Superior, Sister Marcellina Bosatta, he established the foundation of charitable work. He thought it best to transfer the headquarters of the work to Como and in 1886, two sisters and four orphans were sent to Como to begin the mission . This was the nucleus of the future ‘ Little House of Providence’. 

From 1886 this small seed of his Institute branched out into many other institutions. Welcoming the calls of Providence, he founded two congregations: for the women, “Daughters of St. Mary of Providence” and for the men “Servants of Charity” who are all working in different part of the world. He encouraged his confreres and his sisters to work unsparingly, “Charity in all things…It cannot finish as long as there are poor people to serve and needs to be cared for… The whole world is your homeland!”

As a talented writer and preacher, he wrote books, articles, and speeches to present to society the problem of those with disabilities and to further their acceptance as brothers and sisters and as blessings from God. He believed that their disabilities should not separate them from our love and attention and that some things could be done to alleviate their alienation.  Fr. Guanella lovingly called them as “Good children”.

In 1886, Fr. Guanella’s goal became a reality. He opened the first established residential school in Como, Italy, for these beloved “Good children”. In Como he founded the House of Divine Providence which is called the ‘’Cradle of the Congregation’’, at the centre of which he built a Shrine to the Sacred Heart.    
As the work of Fr. Guanella grew and multiplied, his thirsts for doing good did not diminish. In 1912, he came to the United States and toured some of the principal cities. On May 3, 1913, he sent the first six Daughters of St. Mary of Providence to work with girls with intellectual disabilities in Chicago. In support of the dying he founded the Pia Unione del Transito  – Pious Union of Saint Joseph.   He built various churches and worked for emigrants and fringe-dwellers.

On October 24, 1915 at Como, Fr.Louis Guanella ended his days on earth and returned to God, under the wings of whose Providence he had, respectfully and with firmness of intent, walked step-by-step as a true son of the mountains.

He was raised to the honours of the altar and beatified by Pope Paul VI on October 25, 1964 and canonized on October 23, 2011 by Pope Benedict XVI.