Ehninger came from an old Knickerbocker family. After graduating from Columbia College in 1847, he went to Paris and Düsseldorf, studying with Thomas Couture and Emanuel Leutze. Ehninger began his career as both an illustrator and painter, and by the late 1850s had developed a photographic process to make book illustrations from his drawings and those of other artists. A set of his drawings, photographed by Matthew Bradv, were used to illustrate Longfellow's "Courtship of Miles Standish." Another set appeared in an American edition of Tennyson's "Idylls of the King." Ehninger's genre paintings, done mostly in New York City, were post-Civil War renditions of charming country folk in idealized New England and Southern plantation settings. Later on, apparently discontented with urban life, Ehninger moved to Saratoga Springs, New York. In the late nineteenth century, and well into the twentieth, Ehninger's paintings—paeans to disappearing agricultural folkways—were thought to be faithful depictions of the places and people represented. In 1940, Yankee magazine used some of these works to illustrate childhood reminiscences of a contemporary woman.
William H. Truettner and Roger B. Stein, editors, with contributions by Dona Brown, Thomas Andrew Denenberg, Judith K. Maxwell, Stephen Nissenbaum, Bruce Robertson, Roger B. Stein, and William H. Truettner Picturing Old New England: Image and Memory (Washington, D.C.; New Haven, Conn; and London: National Museum of American Art with Yale University Press, 1999)
John Whetten Ehninger graduated from Columbia College in New York and traveled to Europe, eager to soak up the work of the old masters and develop his skills at the European academies. He decided to stay in Germany, and his studies there led him to focus on scenes of daily life throughout his career. Ehninger exhibited regularly and published his illustrations for books by such prominent writers as Washington Irving, Longfellow, and Tennyson.