Pearsall was born in Clifton (near Bristol), England, on March 14, 1795. Though he exhibited musical talent early on (it is said he composed a cantata at age 13), he studied law at the behest of his widowed mother. Then, too, he needed a profession to support his growing family: he had married in 1817 and would soon have three children. He became a barrister in 1821, but abandoned the profession four years later after a mild stroke, which prompted doctors to advise treatment abroad.
He traveled with his family to Mainz in 1825, where he studied music with Joseph Panny. Pearsall was soon writing motets and other works, but also now indulging in his other interests, which included, among many other things, painting and antiques. After returning to England for a year, Pearsall resettled in Karlsruhe, where he lived until 1842. In 1832 he briefly studied early music styles and notation with Caspar Ett in Munich.
In 1834 Pearsall composed Die Nacht eines Schwärmers, described as a ballet-opera, which was performed at a home theater he had built at his Karlsruhe residence.
Soon after returning to England to settle financial affairs resulting from the death of his mother in 1836, he became interested in the composition of madrigals. He joined the Bristol Madrigal Society at its founding in 1837. Though he returned to Germany a short while later, he made periodic visits to Bristol over the next 14 years, often presenting the Society with new madrigals and part songs for performance.
Pearsall relocated to Wartensee, Switzerland, in 1842, having about that time separated from his wife. He befriended some Roman Catholic monks there and near Einsiedeln, and, though he was a lifelong Anglican, began composing sacred music for their services. After another stroke in 1854, his wife returned to serve as her now-weakened husband's caregiver until his death two years later. Pearsall converted to Roman Catholicism in his last days.