Born in New York and educated in New York and Boston, Hewitt began a military education at West Point in 1818, leaving in 1822. It was there that he received his only instruction in music, from the bandmaster Richard Willis.
In 1823, Hewitt joined his father for a theatrical tour of the Southeast, which ended early due to a theater fire in Georgia. Hewitt enjoyed life in the Southeast and began teaching music lessons in Georgia, where remained until 1827, when he returned to Boston, married and began a family.
Hewitt also had a career as a journalist and poet. In fact, while John Hill Hewitt was in Baltimore between 1828 and 1840, he won a poetry competition which Edgar Allan Poe also entered. Well-established as a music teacher by the 1840s, Hewitt continued to travel, taking his family with him, and even gave music lessons to President Tyler's daughter Alice in 1848.
After his first wife's death in 1859, Hewitt remarried and spent the Civil War in Georgia. After the Civil War, he and his family moved to Virginia and then Baltimore, as Hewitt took positions at various colleges.
Hewitt wrote his first musical composition in 1828 ("The Minstrel's Return'd From the War"), and many consider his best song to be "All Quiet Along the Potomac Tonight."