Guido Nincheri was born in Prato, an industrial town about twenty kilometres away from Florence, on September 29, 1885. Determined to study art, he entered, at sixteen, the Academy of Fine Arts in Florence against his father's wishes. There, Nincheri studied decorative and figurative arts, architecture, sculpting, painting, and different art movements, but it was Adolfo De Carolis who had the most influence on the young man's art. It is undoubtedly via De Carolis that Nincheri developed his love of the Pre-Raphaelites, Symbolism, and Art Nouveau (called Stile Liberty in Italy).
In 1910, Nincheri graduated and established his own studio in Florence. We only know of two projects from that period: murals in Stile Liberty at the Società di mutuo soccorso di San Marco (an assembly room for workers' unions) and at a private mansion, the Palazzo Nanni.
In 1913, Nincheri married Giulia Bandenelli and, while he waited for an important project to start, they went on honeymoon on the other side of the Atlantic. Their ultimate destination was to be Argentina, where school friends had relocated, but Nincheri first wanted to visit Boston and New York. They ended up staying in Boston longer than planned, and Nincheri's father eventually advised him to stay in North America because of the persistent rumours of war.
In November, Nincheri and Giulia left Boston and moved to Montreal where the Latin nature of French Canadians was more in line with their own characters. In Montreal, Nincheri found work with Henri Perdriau, the owner of a stained-glass studio. There, Nincheri drew sketches and cartoons for the windows the studio produced, while learning the art of making stained-glass windows. Nincheri’s reputation grew quickly, and within five years he had decorated the baptistery of Saint-Viateur-d’Outremont Church and the apse of St. Michael's Church, had designed St. Anthony of Padua, the Italian church in Ottawa, and was selected to design and decorate Madonna della Difesa.
In 1924, Nincheri opened his own stained-glass studio (located at 1832 Pie-IX Boulevard), which would make some 5,000 windows over the next 45 years. A year later, Nincheri introduced buon fresco, the traditional way of painting murals on wet plaster, to North America. In 1933, Nincheri was named Knight Commander of the Order of St. Sylvester by Pope Pius XI for the propagation of Faith he accomplished through his art and for his generosity towards priests and parishes that had little financial means.
Over the next few years, Nincheri's life was routine, decorating churches across the country and making stained-glass windows with his team of artisans. But everything changed when World War II broke out and Italy joined Germany's side. Declared enemy aliens, Italian-Canadians were arrested in droves and sent to internment camps. Among them was the 55-year-old artist who, against his will, had painted a fresco of Mussolini in Madonna della Difesa Church. Nincheri spent three months in the Petawawa camp. He was freed when his wife, Giulia, proved that the fresco had not been in his original plan.
Soon after his release, Nincheri moved to the United States where he was starting to find work and had just signed an important contract to decorate St. Ann Church, in Woonsocket, RI. He still had his Studio on Pie-IX Boulevard and a country place in the Laurentians, but Nincheri now lived in Rhode Island.
By the time he retired in 1969, Nincheri had decorated more than 200 churches across Canada and New England.
In July 1972, Nincheri received a knighthood from the Republic of Italy. He died on March 1, 1973, at the age of 88.