Koerner’s work was given urgency in 1946 when he learned that his parents, Leo and Fanny Koerner, and brother Kurt, had died in extermination camps. In 1947, Henry Koerner caused a sensation with a show in Berlin, the first exhibition of an artist in post-war Germany and one that dealt directly with war. Returning to the United States later that year, he pursued his painting career to wide acclaim.
In 1953, Koerner settled in Pittsburgh and, until his death in 1991, divided his time between the U.S. and Vienna. Koerner painted over 50 Time magazine covers between 1955 and 1967, including covers of John F. Kennedy and Robert F. Kennedy. He was honored posthumously by retrospectives in Austria National Gallery and the Frick Art Museum in Pittsburgh.