Born at Lucca, he received lessons in music from Alessandro Scarlatti, and studied the violin under Carlo Ambrogio Lonati in Milan and afterwards under Arcangelo Corelli. From 1707 he took the place of his father in the Cappella Palatina of Lucca. From 1711, he led the opera orchestra at Naples, as Leader of the Opera Orchestra and concertmaster, which gave him many opportunities for contact with Alessandro Scarlatti. After a brief return to Lucca, in 1714, he set off for London in the company of Francesco Barsanti, where he arrived with the reputation of a virtuoso violinist, and soon attracted attention and patrons, including William Capel, 3rd Earl of Essex, who remained a consistent patron. In 1715 Geminiani played his violin concerti for the court of George I, with Handel at the keyboard. In the mid-1720s he became a freemason in London, notably as a leading member of the short-lived lodge Philo-Musicae et Architecturae Societas (1725–27) at the Queen's Head Tavern on Fleet Street. He seems to have retained his masonic connections thereafter. On 1 February 1725, he joined the "Queen's Head" lodge in London, becoming the first Italian to be in initiated in the Freemasonry. On 12 May 1725, he became Fellowcraft and Master Mason in the same day. On 11 May 1728, the Grand Master of the Premier Grand Lodge of England James King 4th Baron of Kingstone designated the brothers Geminiani for constituting in Naples the first Italian regular masonic Lodge, directly affiliated to the English Freemasonry.