Early in his career, Jewett was commissioned to paint the portrait of the Governor of New York, which reinforced his position as a painter in the New York area. He moved to California with the Gold Rush in 1849 to take advantage of painting portraits for the newly wealthy. By December of that year, he settled in San Francisco and set up a studio, becoming the city’s first professionally trained painter. He painted portraits of California's prominent citizens and, less frequently, landscapes.
Jewett was born in South Dover, New York, and began painting portraits there by 1833. He studied at the National Academy of Design where his portraits were exhibited during his career. In California, he became wealthy from shrewd real estate investments. He returned to New York City in 1869 and married that same year.