He began studying music at the age of seven. Under the guidance of Maurice Greene, composer and organist at St. Paul's Cathedral, he studied "with great diligence, and a success that was astonishing" (Burney).

At the age of nine he played the organ, probably as an occasional deputy, at All Hallows, Bread Street. The organist died on 23rd September 1723 and exactly one month later eleven-year-old Stanley was appointed organist to the church at a salary of £20 per annum.

In 1734 he was appointed organist to the Society of the Inner Temple - a position he held until his death. It was at the ancient Temple Church that his brilliant playing upon the organ and harpsichord attracted the attention of many fine musicians including Handel who regularly visited the church to hear him.

In 1738 Stanley married Sarah Arlond (daughter of Captain Edward Arlond of the East India Company) who brought him a dowry of £7,000 per annum. Sarah's sister Ann, who at this time lived with them, became the blind composer's copyist.

After Handel's death in 1760 Stanley began a partnership with the composer John Christopher Smith in order to continue with the performances of oratorios at Covent Garden. For the first season Stanley composed 'Zimri'. Stanley accompanied all oratorios, and played a concerto during each interval.

Continuing yet again in Handel's footsteps, Stanley was elected a governor of the Hospital in 1770, and from 1775 until 1777 he directed the annual performance of Handel's Messiah in aid of the hospital funds.

In 1779 Stanley succeeded William Boyce as Master of the King's Band of musicians. In this capacity he composed many New Year and Birthday odes to the King but unfortunately this music has not survived. Stanley's last work was probably an ode written for the King's birthday (4th June 1786). Stanley never heard its performance - he died at his home in Hatton Garden on 1786 aged 74.