He was born in Montreal and received his musical education in St. Matthew's Anglican Church, Ottawa, the University of Ottawa, King's College, Cambridge and the Royal College of Music in London, England. The sometime organist of Westminster Abbey, the Australian-born Sir William McKie, who lived during his last years in Ottawa and who was Finley's great-uncle, encouraged him in his early musical activities.
He is particularly renowned for his interpretations of Mozart roles such as Guglielmo, Papageno, Figaro, the Count and Don Giovanni. He made his New York City debut at the Metropolitan Opera on January 24, 1998 in the role of Papageno in Die Zauberflöte. He has subsequently performed the title role of Don Giovanni, Marcello in Puccini's La bohème, and the title role of Guillaume Tell at the Metropolitan Opera.
In addition to his success with Mozart, Finley has been active in contemporary opera. He has created a number of roles including Doctor Oppenheimer in the world premiere of John Adams' opera Doctor Atomic at the San Francisco Opera on October 1, 2005. This opera had its Metropolitan Opera premiere with Finley in the Oppenheimer role on October 13, 2008 and was broadcast as part of the Met's Live in HD broadcast series on November 8, 2008. Other roles he has originated include Harry Heegan in The Silver Tassie by Mark-Anthony Turnage at the English National Opera and the title role in Fantastic Mr. Fox by Tobias Picker at the Los Angeles Opera.
Finley has been critically praised in both opera and concert. After a recital at Carnegie Hall in March, 2007, he was praised by New York Times critic Bernard Holland as having a "bass-baritone of easy luxury" and that his "sensibilities begin with the pre-eminence of words." His portrayal of Schumann's Dichterliebe at the Wigmore Hall in 2006 was also highly praised.
Expanding his repertoire, Finley sang the title role of Eugene Onegin at the Royal Opera House, Covent Garden in March 2008. This was the second time he has sung a Tchaikovsky role for the Royal Opera; the first being Prince Yeletsky, from Pique Dame. In 2011 he sang Hans Sachs in the Glyndebourne Opera production of Die Meistersinger von Nürnberg to much critical acclaim.
Finley appears on a number of recordings, including several solo albums on the Hyperion label.
In June 2014, he was made an Officer of the Order of Canada.
In October 2014 he opened the Canadian Opera Company 2014-2015 season as the title character in Falstaff. It was his return to the company after an absence of 20 years and his first appearance as Verdi's Fat Knight.
On May 14, 2015, he performed the world premiere of True Fire by the Finnish composer Kaija Saariaho, which the composer dedicated to Finley.
Finley was appointed Commander of the Order of the British Empire (CBE) in the 2017 Birthday Honours (UK) for services to opera.
Finley's many recordings include:Franz Schubert: Winterreise, accompanied by Julius Drake (Hyperion, 2014)
Songs by Samuel Barber, accompanied by Julius Drake (Hyperion, 2007)
Maurice Ravel: Songs, accompanied by Julius Drake (Hyperion, 2009)
Wigmore (Hall) Live, Songs by Tchaikovsky, Musorgsky and Rorem, accompanied Julius Drake (Wigmore Live, 2008)
Ives: Songs (vol.11), Romanzo di Central Park with Gerald Finley, accompanied by Julius Drake (Hyperion, 2008)