John Stanley was born in London on 17 January 1712. At about the age of two, he fell on a marble hearth with a china basin in his hand, an accident which left him almost blind.
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. When he was eleven years 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 which he held until his death in 1786. It was at the ancient Temple Church that his brilliant playing upon the organ and harpsichord attracted the attention of many fine musicians including George Frideric Handel, who regularly visited the church to hear him. Stanley was also an outstanding violinist.
Though virtually blind, Stanley had a remarkable memory, which helped him direct many of Handel's oratorios and to enjoy music-making and card games with his many friends.