His debut as a cinematographer he gave in 1915 with the short film Last Night of the Barbary Coast, which he also directed, together with Sol Lesser itself.
From 1930 to 1931, from 1963 to 1965 and from 1969 to 1970 he was the president of the American Society of Cinematographers.
In 1936 he won the Oscar for his work on A Midsummer Night's Dream ( A Midsummer Night's Dream ), making it the first and only person who won an Oscar, without having been nominated. Eight years later, he shared with W. Howard Greene for Phantom of the Opera his second trophy.
In his honor, there is a star on the Walk of Fame.
Hal Mohr was married twice. His first marriage felt about 1926 until 1929. Five years later he married the actress Evelyn Venable, this marriage lasted until his death. Together they had two children.