David Jewitt was born in the United Kingdom in 1958 and studied astronomy at University College London. In 1979, he began post-graduate work at the California Institute of Technology in Pasadena, winning a doctorate in 1983. His first job as an assistant professor began the same year at the Massachusetts Institute of Technology in Cambridge, and it was there that he began his Slow-Moving Objects (SMO) survey in collaboration with Jane Luu that would eventually lead to the discovery of the Kuiper Belt.
In 1988, during the course of the SMO survey, Jewitt moved to the Institute of Astronomy at the University of Hawaii as an associate professor. He continued to work there and at the university's Department of Physics and Astronomy until 2009, when he moved to the University of California, Los Angeles, as a professor in the Department of Earth and Space Sciences. In 2011, Jewitt was appointed director of UCLA's Institute for Planets and Exoplanets.
In 1996, Jewitt was named Hawaii Scientist of the Year and awarded a NASA Exceptional Scientific Achievement Medal. In 2005, he was made a fellow of the American Association for the Advancement of Science and the American Academy of Arts and Sciences, and a member of the U.S. National Academy of Sciences.