Born Jakob Ludwig Felix Mendelssohn-Bartholdy on February 3, 1809, in Hamburg, he was the grandson of the noted Jewish philosopher Moses Mendelssohn. (The name Bartholdy was added to his surname when the family inherited property from a relative of that name, but he was always known by his original name.) As a child he converted with his family to Protestantism.

Mendelssohn first appeared in public as a pianist at the age of 9 and performed his first original compositions when 11 years old. His masterly overture to A Midsummer Night's Dream was composed at the age of 17; the famous "Wedding March" and the rest of his incidental music to the play were written 17 years later.

His teachers included the Bohemian pianist-composer Ignaz Moscheles and the German composer Carl Zelter. A revival of public interest in the works of Johann Sebastian Bach was directly attributable to Mendelssohn, who in 1829 conducted the first performance since Bach's death of his Passion of St. Matthew.