Christensen taught art at BYU from 1976 until 1997.
He has had numerous showings of his work throughout the US and has been commissioned by media companies to create artwork for their publications, such as Time-Life Books and Omni.
His artwork has been featured on the cover of Leading Edge issue #41, winning him the Chesley Award for cover artwork in 2002.Christensen's work has appeared in the American Illustration Annual and Japan's Outstanding American Illustrators. He also won all the professional art honors the World Science Fiction Convention offers, and multiple Chesley Awards from the Association of Science Fiction and Fantasy Artists.
Christensen has published more than three books, with many of his works appearing in many more. His first book, A Journey of the Imagination: The Art of James Christensen, was printed in 1994 to great acclaim. His second, Voyage of the Basset (October 1996), contains a frame story for a great deal of original work. His third book, Rhymes & Reasons, was published in May 1997. Christensen also illustrated A Shakespeare Sketchbook (May 2001) with text by Renwick St. James.
While not employed in all his paintings, his trademarks were flying or floating fish, often on a leash.