Tenor and songwriter Geoffery O'Hara was born in Chatham, Ontario, and moved to the United States in 1904, becoming a naturalized citizen in 1919. After working in a bank for a few years in Canada, he became an entertainer, doing minstrel work and performing on vaudeville stages. His first recordings are from 1905. The July 1905 issue of Edison Phonograph Monthly announces the August release of "The Rosary" (Edison 9052) sung by the Knickerbocker Quintet, which consisted of Parvin Witte, Charles H. Bates, O'Hara (he is surprisingly listed as a baritone), Walter C. White, and Leon Parmet. O'Hara reported to Jim Walsh that he made Zon-o-phone records in 1906-07 as second tenor of a quartet.

He wrote many songs recorded by others. "Your Eyes Have Told Me What I Did Not Know," written with Fred G. Bowles, was recorded by Enrico Caruso on April 10, 1913. Issued on Victor 87159,it was one of the few numbers with lyrics in English cut by the tenor. It was a curious selection, a case of an extremely famous singer covering a number by two unknown songwriters. It was probably selected because its lyrics are simple and therefore can be understood when sung by this Italian whose English was limited (the long title is the song's first line, which also helped). The song is otherwise unremarkable. No other singers recorded it. The disc sold well only because it featured Caruso's voice.

In 1918 O'Hara composed the very popular "K-K-K-Katy." Enlisted men evidently enjoyed singing it, and several artists recorded it though the song was most associated with Billy Murray, who covered it for Victor and Edison. "There Is No Death," which became a traditional song for Armistice Day after the song was introduced in 1920 (Gordon Johnstone provided the lyrics), was recorded by Lambert Murphy (Victor 45175), Charles Hackett (Columbia 78930), and Richard Crooks (RCA 10-1216).

Other O'Hara compositions include "Highlanders! Fix Bayonets," written with William J. Pitts and sung by Edward Hamilton (a pseudonym for Reinald Werrenrath) on Victor 17775; "I'm a Jolly Old Rover," written with T. E. B. Henry and sung by Wilfred Glenn on Victor 18025; "The Blush Rose," written with Schuyler Greene and sung by Lambert Murphy on Victor 45126; "Give a Man a Horse He Can Ride," which was O'Hara's setting of a James Thomson poem (Royal Dadmun sing sit on Victor 45266); and "All Erin is Calling Mavourneen," written with Katherin Ward and sung by Charles Harrison on Victor 18111. On the rare Victor 6536 from the late acoustic era Red Seal baritone Emilio De Gogorza sings two O'Hara numbers, "De Captaine of de Marguerite" and "Leetle Bateese."

O'Hara visited Navajo reservations in Arizona with an Edison cylinder machine and recorded Native Americans singing. He sang Navajo Indian songs in 1913 for the Victor Educational Department and issued in late 1914 on Victor 17635. He sang several Indian songs (with tom-tom accompaniment and explanatory comment) for Edison, issued as Blue Amberol 2451 in November 1914. The October 1914 issue of Edison Phonograph Monthly announcing this cylinder lists O'Hara as a baritone.

The tenor made black label Victor discs that were issued in 1916. Songs covered include Charles K. Harris' "All I Want Is a Cottage, Some Roses, and You" (18022) and Egan and Whiting's "They Made It Twice As Nice As Paradise (And They Called It Dixieland)" (18051). He also recorded with contralto Lillian Davis (really Marguerite Dunlap) in 1916 one of his own compositions, "Ma Li'l Starlight" (Victor 18166). He served as musical director at Fort Oglethorpe during World War I. In late 1917 he recorded "The South Will Do Her Part" (18391), a patriotic reworking of "They Made It Twice As Nice As Paradise (And They Called It Dixieland)." The last Victor recordings of O'Hara performing as a solo artist were issued in July 1918: "A Soldier's Day" backed by "Parodies Of The Camp" (18451). In 1919 in Canada he recorded two songs that were issued on Canadian Victor 216059, "Burmah Moon" and Doughboy Jack and Doughnut Jill," both written by Gitz Rice.

The last commercial disc with O'Hara's voice was Victor 35937, which features "Over Here" and "Over There," two medleys of World War I songs cut by the Victor Male Chorus on September 13, 1928. Oddly, Frank Crumit instead of O'Hara himself sings "K-K-K-Katy" for the medley. O'Hara sang the verse of George M. Cohan's "Over There."

He taught at Teachers College, Columbia University, in 1936-37. He also taught at the University of South Dakota. When Walsh wrote about O'Hara for the February 1960 issue of Hobbies, O'Hara lived on South Quaker Hill in Pawling, New York. He married Constance Margaret Dougherty in 1919 and they had two children, son Hamilton Murray and daughter Nancy Jackson. He died in St. Petersburg, Florida.