Porpora was born on August 17, 1686, in Naples. He showed talent early in his childhood, and at the age of ten was placed in the Conservatorio dei Poveri di Gesu Cristo. Not much is known about his teachers there, but upon his departure he was well-grounded in voice and composition. His first opera, Agrippina, came in 1708, though he took three years to produce his next significant work in any genre.
By 1711, Porpora had become maestro di cappella under the Prince of Hessen-Darmstadt at Naples, and two years later, following the departure of the Prince for Austria, the maestro di cappella for the Portuguese ambassador. Porpora was well connected then, even receiving a Viennese Court commission for his opera Arianna e Teseo (1714). Four years later he provided another opera, Temistocle, for that same court. Around this time, the composer was also coming to be regarded as one of the finest teachers of singing in Italy, his pupils including the castrato Caffarelli.
By the early 1720s, Porpora's reputation throughout Italy as a composer was growing as well, owing in great part to a string of successes in Rome. He settled in Venice in 1726 to teach at the Ospedale degli Incurabili. Perhaps sensing a decline in his art, he departed for London in 1733 at the invitation of some English patrons. He would write five operas in London, including Arianna in Nasso (1733), and other vocal works, like the serenata La festa d'Imeneo. He left England in 1736, having achieved many successes there.
The composer returned to Italy and held a series of posts over the next decade, perhaps divulging a certain restlessness, and perhaps insecurity. In Naples, he accepted the position as maestro di cappella at the Conservatorio di Santa Maria di Loreto in 1739; in Venice he was appointed similar posts in 1742 and 1743, none served concurrently. After unsuccessfully seeking yet another maestro appointment in Naples, he traveled to Dresden to serve as court kapellmeister and teacher to Maria Antonia, the Electoral Princess. He departed around the beginning of 1753 and traveled to Vienna, mainly as it turned out, to teach. His most prominent student there was the young Haydn
. Owing to dwindling finances, Porpora returned to Naples in 1760 to serve as maestro di cappella again at the Conservatorio di Santa Maria, and later at the Conservatorio di Santo Onofrio. He resigned all posts the following year and lived in poverty until his death in 1768.