He was born in Chatham, Ontario, Canada. He moved to the USA in 1904. He performed on Vaudeville and recorded for Edison Records.
O'Hara wrote a number of hymns and spirtual songs.
He had some moderate popular music hits in the 1910s with songs such as "Your Eyes Have Told Me What I Did Not Know" and "Tennessee, I Hear You Calling Me", and one huge popular hit with his 1918 song "K-K-K-Katy", one of the most popular tunes of the World War I era.