Ponchielli was born in Paderno Fasolaro (now Paderno Ponchielli), Italy, on August 31, 1834. His father was a good amateur organist who gave young Amilcare his first lessons. After showing remarkable advancement, he began study with an organist from a nearby village. At the age of nine, Ponchielli was taken into the Milan Conservatory, where he would remain, tuition free, for 11 years. There he began study with Arturo Angeleri on piano and Pietro Ray in music theory. At age 10, the precocious Ponchielli wrote a symphony in piano score.
In 1851, he began instruction in composition with Felice Frasi, and was already delving into opera. His first flirtation with it came when he collaborated with three other students in the 1851 effort, Il sindaco babbeo. After graduating from the Conservatory in 1854, Ponchielli took an organist position at a church in Cremona, not far from his native Paderno. The following year, he became assistant to the director of the Teatro Concordia. It was here that his first opera, the aforementioned I promessi sposi, was staged in 1856 with some success. Over the next 15 years, Ponchielli struggled to achieve a significant triumph, but his operas either failed (sometimes to even reach the stage) or had success only in provincial opera houses.
In 1864, he became conductor of the Cremona municipal band and started work on his ballet, Grisetta (1864-1865). While it was a mild success, he wanted to focus his attention on opera. Eventually he returned to I promessi sposi, which scored a success in its revised version in Milan in 1872. Soon it was taken up by many other theaters in Italy, and in the meantime Ponchielli found an ally in the publishing world when Ricordi began issuing his music scores. In addition, his recently composed ballet, Le due gemelle, was staged at La Scala in 1873 and scored a major success.
Ponchielli had now emerged as one of the leading composers in Italy. In 1874 he married soprano Teresina Brambilla. Together they had three children. Ponchielli's reputation was bolstered further in 1876 by his greatest triumph, La gioconda, with libretto by Arrigo Boito. The work would be taken up by opera houses all over Europe, as far away as St. Petersburg, where Ponchielli would attend performances in 1884. In 1880, following further successes, he was appointed head of composition at the Milan Conservatory and, in 1881, maestro di cappella at the Bergamo Cathedral. He died five years later, on January 17, 1886.