Locatelli was one of the leading Italian violinists and composers in the first half of the eighteenth century. At one time, he was known as the "Paganini of the eighteenth century" due to his 12 concertos and 24 caprices for violin. Although he was known primarily as a virtuoso violinist in the early part of his life, his abilities as a composer were far more important. Stylistically, Locatelli worked within the conservative forms of the composers of the Roman school (Corelli, for example), but incorporated many of the more progressive elements of the Venetian school (Vivaldi, above all). He wrote mostly sonatas and concertos for string instruments, although there is a set of flute sonatas, and a lost concerto for wind instruments with strings. With the exception of those flute sonatas, Opus 2, which occasionally have three movements, his other works were almost exclusively in the older four-movement format. Locatelli also made the written-out cadenza a standard part of his violin concertos, an innovation from the earlier practice of exclusively improvised cadenzas. In general, though, his style was a consolidation of existing trends, yet still original in the beauty and resourcefulness of its harmonies.
Very little is known about Locatelli's early life and training, other than that he held a post as violinist in Bergamo until 1711. By 1712, he was in Rome, probably studying with Giuseppe Valentini, Corelli's rival. During the subsequent years, Locatelli worked exclusively as a violinist, particularly at the basilica of St. Lorenza in Damaso, Italy. In 1725, he was appointed virtuoso da camera of Mantua, a position which allowed him free rein to travel as a virtuoso.
In 1729, Locatelli moved permanently to Amsterdam, where he devoted his attention to teaching and composing with an occasional concert tour. He was also involved in importing Roman violin strings and in publishing. By his death in 1764, Locatelli had been successful enough to leave behind a considerable estate, as well as a compositional legacy that remained fairly current until the beginning of the next century.