Willard Richards was born 24 June 1804 in Hopkinson, Massachusetts, to Joseph and Rhoda Richards. He was the youngest of eleven children. At the age of four, he fell from a scaffold and injured his head, which may have caused the muscle tremor and paralysis from which he suffered throughout his life. This injury also limited his physical ability to work on the farm, and he turned his attention to book learning, which he enjoyed immensely.

In 1813, at the age of nine, Richards moved with his family to Richmond in western Massachusetts. He continued his schooling and obtained a teacher's certificate at age sixteen. He taught school in Chatham, New York, and in Lanesborn, Massachusetts. He completed additional studies and experimentation in the fields of mechanics and science, which led to his lecturing in the surrounding areas on these subjects. During this time he also developed his musical talents and performed as a clarinetist with the Massachusetts Militia Band.

When his sister Susan died of a mysterious illness, Richards took an interest in the study of medicine, including herbal remedies. At the age of thirty, he spent two months at the Thomson Infirmary in Boston, after which he was commissioned as an agent for Thomson's Patent Rights herbal medicine. He then settled in Holliston, Massachusetts, where he practiced medicine and became known as Dr. Willard Richards.